My best six cavediving events of the easter 2002 Mexico trip were as follows. (1) All the "four Doors" Cenotes. A delicate sidemount dive downstream of the Grand cenote. (2) Round trip Cenote Calimba -> Cenote Pabilanny. A long multi-stage-bottle dive into the very heart of the far upstream section of Sak Aktun system. (3) Cenote Jailhouse. A "little treasure". (4) Lithium Sunset done properly. A follow up dive from one I did with Brent and Joe, when we found the main passage into the recently discovered "Lithium Sunset" area of Sak Aktun, but didn't have time to explore. (5) Round trip Cenote Calimba -> Cenote Bosh Chen. Nothing technically demanding about this one - it's just beautiful! (6) At the very end of the trip I had a chat with Bill Phillips, master explorer and cartographer of (among others) Sak Aktun. I dared to ask, and he invited me, to come exploring with him next time. Watch this space!! [ I wouldn't have dared to ask if Events (1) and (2) hadn't gone well because that's stuff that he found; and it seems to me if you can't do it as a tourist dive, you ain't ready to explore it yet.... so I shall practise my as-yet-non-existent surveying skills, and also improve my sidemount gear. ] here are the logs of events 1 to 5. Dive 24 (and last of trip). All the "Four Doors" cenotes. Cracking the sidemount restrictions immediately downstream of Grand Cenote. 94 minutes, max 33 feet, 75F, solo. A good dive for last dive of trip, nice and shallow so not to prejudice chances of avoiding DCI during plane flight home the next day. The classic parts of the Sak Aktun cave system all lie upstream of the main entrance point, the Grand Cenote. Nestling in an odd spot around the walls of Grand Cenote, though, is a downstream continuation which for many years was undiscovered. Recently it has been explored by Bill Phillips, Dan Lins and others, and has been connected to Cenote Naval, just under 2 miles downstream. Much of that 2 miles of passageway is open passageway perfectly suitable for backmounted doubles. But at the Grand Cenote end (and also, from the map, nearer the Cenote Naval end) there is a sidemount only passage. In fact, a passage of about 1000' involving not one but several no-kidding sidemount-only restrictions. "About as tight as it gets" - I quote Bill Phillips, cavediving instructor, explorer and cartographer. To this thousand feet of passageway, therefore, I turned my attention for the last dive of the trip. I donned my drysuit, which is my buoyancy control when sidemounting, attached my tanks to my weightbelt at the bottom ends and some bits of nylon string at the top ends; I clipped safety reel, backup lights and backup regulator to the same bits of string, and headed for the entrance. This ultra-crude sidemount gear has one definite advantage. It keeps me very slim in the restrictions, no Transpack, and no butt- or side-mounted battery canister to jam in the rocks (Brent has a story or two along those lines and yes, I was listening carefully when he told them!). My divelight has its battery in with the light head. And to cut a long story short, I aced the whole section!! - passing all four major restrictions, visiting all five intermediate cenotes, and finally breezing down a little of the more open, backmountable passageway before calling the dive a little ahead of thirds - after all, this is a siphon passage with flow and restrictions, even if there is a profusion of alternative exits to air. Boy was I pleased.... here are the details. It begins with a backmountable section for a few hundred feet, from Grand cenote to Snake Cenote. There's a T (the lines meet) with the main passage going right. Leaving Snake Cenote along the main passage towards Four Doors Cenote #1, one encounters the first restriction that's marked sidemount-only on the map. I think, though, that one could pass that one in backmount, at the expense of wallowing in mud and silting out the passage. Then one gets to the pretty little Four Doors cenote #1, and turning to pass towards Four Doors cenote #2, one gets the first no-kidding restriction, the Twister restriction. First one gets a winding area between bedding planes where the gap drops to maybe 12 to 18 inches; then a narrow triangular hole with the base at the bottom tapering to a point at the top. One wriggles the sidemount cylinders towards the two bottom corners and wriggles through oneself. It is a bit harder on return, though, because the flow is concentrated in the narrow space and it's a bit like getting out of the July Spring passage in Florida, the flow not as great but the passage much more restricted. One pulls and wriggles ones way back. Emerging at Four Doors Cenote #2, there is an unrestricted passage to Four Doors Cenote #3. Then, betweeen Cenotes 3 and 4, one hits the hardest restrictions of all, the two Mouler restrictions (the one I tentatively identified as the pickpocket restriction is relatively easy, you just avoid damaging the decorations). It was Mouler #1 that stopped me when I attempted this dive with the sidemount cylinders attached to a solid backplate. The backplate jammed in the crack. Mouler #1. I think, the hardest of them all. A narrow slot between bedding planes, maybe 15 inches high at the left hand end, tapering to 9 inches or less at the right end, with odd bumps in the floor at just the right places to obstruct the natural way of hacking it sidemounted. So, squeeze over to the left a bit and let that bump lie between my body and Cylinder Right. Push/Pull the body through, body moving OK, both cylinders jam on bumps in the rock. Where's my spare regulator in this blizzard? I just might need it if something happens to Reg One, such as being forcibly ripped out of its first stage by excessive wriggling in the restriction. Touch the spare reg; nice and reassuring, but got to let it go, I need the right hand to grab the neck of Cylinder Right and pull it away from the bump that's causing the jam. Still jammed... moving a little... wriggle a little... got it! What's happened to Cylinder Left? Much the same I suppose, comes free with a bit of twisting, rather less than with Cylinder Right. Move forward again. I'm through! And the cylinders, yes, they can pass more easily now they're sharing the crack with my legs rather than my torso. Done it! Now where's the guideline gone? It must be within 2 feet but is totally invisible in the silt-out. Wait 30 seconds. A glowing thread of guideline on my right becomes dimly illuminated. 30 seconds more and a rock or two becomes visible, also a couple of feet away. Thank God we've got significant flow in here! Slowly move on. The passage becomes clearer. A couple of twists and turns and (just as you thought it was safe to go back into the water??) you come to Mouler Restriction #2. At this point I nearly gave up because Mouler #2 looks even worse than Mouler #1. I can believe that the average height between the bedding planes is less than for Mouler #1. BUT the height is CONSTANT, the bedding planes are PARALLEL, the gap doesn't taper to one end as it does in Mouler #1; and also the bumps in the floor are much less. So when I tried it, I in fact wriggled through Mouler #2 with no trouble at all. Four Doors #4 cenote is a few more twists and turns down the passage. Glorious greens and blues and sunlight. Below Door #4 the passage is initially lowish from floor to ceiling, but widens out and becomes pretty, moderately decorated with dark silt floor, and eminently backmountable. As mentioned before, I turned the dive a little early, 2000/3000 in one tank and 2200/3000 in the other, because the restrictions were over, the battle was won - and just in case one of the previous restrictions took 25 minutes to pass on the way back. They didn't! I even passed back quickly through Mouler #1. Visibility clear ahead because on RETURN it is a quite-swift UPSTREAM passage. Slight squeezy hassle passing the triangular bit of the Twister against the flow. No real problem. Back past Snake cenote. Back into the sunlight at Grand Cenote. Victory!! Dump the cylinders at the surface. Say Hi to some Latino tourists. Empty 4 pints of water out of "dry" suit. It was non-leaking earlier on but swiftly began leaking when I started dragging it through sidemount restrictions. Still working as a BC though; and I wear a 4mm wetsuit under the drysuit which can cope with 4 pints of warm Mexican water very nicely, thanks very much. Who cares? Done it!!! Final exit pressures, 1000/3000 and 1300/3000 PSI. * My first really ace sidemount dive. * In a different sense from Dive 22, a new kind of challenge. Dive 22. Cenote Calimba -> Cenote Pabilanny round trip. 209 mins, max 44 feet, 75F. Solo. Note: this dive can, and with a team of divers probably should, be done with 2 stages; but I, totally unfamiliar with the far upstream end and solo, allowed myself three for a 209 minute dive including 21@10 deco (The dive was preceded by an 83 minute setup dive in which the third stage bottle was placed at a suitable point in the paso de los Dos Pozos upstream of the Calimba snap-and-gap. I placed it when my doubles had been breathed to Thirds so the stage was well forward in the system, which is where I believe a stage should be, so it's closer to hand if there's trouble at the remote far end) This dive begins with the beautiful Calimba, which however you can only partly spend your time on because you must pay attention to your two stage bottles (or stage and buddy bottle if you prefer - one will get dropped shortly). Coming out of the brilliantly decorated Calimba, into the more normal Paso de los dos Pozos, one presently catches up with the stage bottle dropped on the previous dive and one makes a swap, the dropped bottle having been breathed to thirds. Continuing down the varied passage, some plain, some decorated, some minor restrictions, one comes first to a junction involving two red arrows a foot apart; then, a very short while later, to the single orange arrow which marks the one and only jump in this long dive. Deploying a (primary!) reel one proceeds into the restricted area called the trap Door which leads to the far upstream section. Good job it's undecorated, there was plenty of clanging of tanks as I went through it. One follows the line until one comes to an all-lines-meet Y junction where one takes the left branch that leads into the Pabilanny passage. Then another three-lines-meet Y with a fourth line a foot away on the left, and one takes the right branch of the Y (that's where I made a navigation error on a previous attempt at this dive plan). All quite open, unrestricted passageway. A little while later I judged that with 2000 PSI left in my doubles it was now safe to drop a second stage bottle (with 2400 PSI left in it) and continue until I had 1200 PSI left in my doubles (the buddy bottle having already been breathed down to 2400 PSI). [ my air planning for the dive was to have 1200 in my doubles = 2400 in the buddy bottle = 2400 in the second dropped stage at turnaround; any two of these would very comfortably get me back to the first dropped stage, and with the favourable tail wind would in fact have got me right out of there. This is a variant of the thing I do when solo of breathing the doubles down to halves and taking nothing from the buddy bottle, so either of them will get me out.] A little further ahead and - what a joy! - the line arrows change direction, indicating that I'm now close to Cenote Pabilanny. And as if to reward a long dive, the passage becomes superlatively decorated - the decorations really a feast to the eye - I was glad I was down to one buddy bottle so as not to damage the decorations - and then the ascent begins, you find yourself going up a nearly vertical wall, and at the top you're among tree roots, still with fine decorations around you. Finally you see daylight and surface at the cenote - you are at the bottom of a 12 foot chimney with sunlight at the top. There are ropes in the chimney so plainly some of the exploration of this section was done from cenote Pabilanny [In fact not so! Bill Phillips says he set the ropes up but didn't in fact use them] In fact I got to Cenote Pabilanny with about 1500 left in my doubles. Thus, there was plenty of air for the exit. Good job too, because I got back to the first dropped stage, all prepared to do a nice cool swap with the now-down-to-500-PSI second one - & found it was missing an O ring (I was swapping regulators from stage to stage because the whole dive had to be accomplished with only three regs). Not only that but I discovered this after I had removed the reg from Stage Two, and in the heat of the moment I couldn't get it to fit back on to Stage Two without leaking. So, I was minus 2500 PSI of a single from total air supply unless I paused and fixed something. Not too threatening, the safety margin in my air supply could handle it comfortably; but enough to set me thinking and convince me not to play that game of swapping the regs except in emergency. Buy an extra couple of regs, Charles! You know it makes sense!! I carried the extra stage all the way back to the Calimba entrance just in case something else happened and I was forced to get fixing. Just inside the Calimba I know 800 PSI in doubles or 1600 in a stage gets me out comfortably; now my doubles had 1000 and my buddy bottle 1750. Stage One was gratefully clipped to the line and left at that point. My 100% redundancy was mercifully restored without it, or the 500 PSI in Stage Two either. The return trip through the Calimba was uneventful, though by the end of the 21@10 deco my primary light was dimming. Leaving it on as I climbed out, I saw it dim to a glowworm thread within the next 20 minutes or so. I tried again to get Stage Two to fit properly; and of course, with the pressure now off, it worked. * My most challenging dive yet. * One of my best dives yet - perhaps the best. * beautiful at the start (Calimba) and finish (Pabilanny). * my longest single dive (209 minutes) and longest total day's diving (292 minutes). * Certainly my furthest penetration yet - how far I'm not exactly sure, I might ask Bill Phillips, one of the original explorers, who lives just down the road. [But in fact I forgot to do so]. * I retrieved the first stage bottle (minus its O ring) the following day, just before Dive 24 in fact. I had dropped it again just inside the Calimba passage. D8. Tuesday. Jailhouse Cenote. Buddy Peter Vogt. Team of 4 with the other pair Erich and Joe. This cenote is a little treasure, part of the Naharon/Mayan Blue system but a 6 minute walk into the jungle from where you can park a car. But its upper (30-40') level is pretty, and its lower (ca. 70') level is awesome, with magnificent limestone columns, and a Mayan skeleton pretty complete, which must date from when the water level was lower, and the cave at least partly dry. An excellent dive. 78 mins, max 74', 76F. The skeleton was found due to Joe's knowledge of the cave. You wouldn't just run into it. Dive 16. Saturday. Lithium Sunset done properly. 150 minutes, max depth 58', 6@10 deco, 2 stage bottles. 150 minutes of pure joy as I returned to the Lithium Sunset passage and did it properly (we didn't really get far into it on D10). Really well decorated, delicate rooms dwindle into cheesy salt passages. I turned the dive when my computer said "57', deco in 3 minutes" - the map shows the passage continuing a little further, to a max of 60 feet depth, but I had done most of it and didn't want to be hit with too much deco. Besides, I was beginning to feel cold [later long dives I wore my drysuit]. This is a 2-stage-bottle dive, at least if you breathe at my rate and are solo (air management better be on the safe side). I dumped the first one at the T where the more southerly route into Lithium Sunset turns off left. Of course I kept my buddy bottle, which was the second stage. Now the choice of place to dump Bottle One was made as follows: it is impossible to get to that T on one third of a stage bottle. But I dropped it there nonetheless because it is my belief that when a stage bottle hits thirds you should breathe something else, but continue carrying it further into the cave in case you need it in a hurry on the way out; preferably carry it until it would have hit two thirds if you'd been breathing it all that way, so it's at the furthest point from which you can exit using that stage alone if push comes to shove (as we all hope it won't). The Lithium Sunset T about fitted that description. A small point, which I wouldn't insist on if I had a buddy, but feel is important when I'm solo. I don't wish to stir sad memories, but if a certain stage bottle had been 150 feet further in to a certain cave, a very nice man called Steve Birman might be with us to this day. I went up the paso de Lagarta, jumped off left as in D10 circa 300' after the jumpoff to Much's Maze, and then jumped left at the T because that was a route into Lithium Sunset that I hadn't seen before. This goes round and meets the main line into Lithium Sunset where I jumped back onto it (turning left). Once in the Lithium area I turned R. at the first (lines-meet) junction then R. again at the second, turning after 77 minutes, with depth 57' and penetration circa 3400 out of the possible 3723. 75F. profile 18,36,36,38,37,39, 36,37,38,40,40,38,39,38,39,38,39,39,39,40,38,38,45,55,57,58,50,37,39,39,39,39, 38,39,38,39,38,40,38,37,39,38,38,37,35,20,13,14,8. D14. Friday. Cenote Calimba -> Cenote Bosh Chen. Buddies Lazarus (I mean Jeff) and Marion. It was extremely nice to see Jeff diving again, though strictly this was against doctor's orders (*). We went to the end of the Calimba line, jumped right onto the main (top end of the paso de Lagarta) line for a few feet, then off to the left and the Bosh Chen line. Took also the next left jump that makes a loop via Bosh Chen. Very lovely. Circa 105 minutes. (*) he had had a skin bend 3 days ago. *************************