It's fair to say that I spent a lot of today on my back.

I awoke sporadically through the night, usual when I don't want to oversleep. Properly awake at 0500 so give up trying. Go for a walk at 0600 and buy some suncream, then a quick walk around, the sun rising, the air fresh. Check out, at 0640, the sun now up - extremely hot already. Reach the port. 'Boarding begins at 0715' proclaims a sign, and since that is 25 mintues away I go for a walk, past restaurants to the end of a pier, looking across at some high hills.

Check in, pay $10 for wetsuit hire and eat the supplied bacon and egg roll (which would later turn out to be a bad idea - I should have known, as I don't like egg.) The boat departs and all is dandy, a beautiful view as we pull out of Cairns, gushing waves in the slipstream of the boat - a little Catamaran - and even see a couple of dolphins jumping out of the water. Then queasiness sets in, so I lie down, clutching my camera, and shut my eyes. Bearable. We slow as we arrive at the boat-swap, and move to the boat which will be home for 24 hours. Our baggage is passed over and after a few minutes we are shipped round, on a little dinghy with a small motor, to board the vessel. After a brief introduction we are shown to our dorms. I'm in a room with two girls, and although I'm offered another room I stay, more sociable. Down some steep steps to Room 101 - is this ominous? - will I end up wanting to put this experience into my own personal Room 101?

Then, at 1030, our first adventure: donning the watersuit for the first time. Feeling a little like James Herriot on his first trip to see Angus Grier, I descend to the jumping in area. We have to sign out and in every time so they always know where people are at a given time. Pulling flippers and snorkel on, I sink into the sea and begin to examine the Great Barrier Reef!

It is bizarre and wondrous simultaneously, fish and coral living together, colours changing by the second. Some corals throbbing, others huge and alien like, the fish flitting between them - large, small, long, short. One moevs past, a lovely turquoise and blue, another similar but more of a real purple. What look like Zebra fish, some yellow and black ones. You can swim yourself around, or you can relax and let the current take you where it will. Time has no meaning here, nor should it - I have no idea how long I was out but it was probably 45 minutes. All thoughts of queasiness have passed.

Back on the ship, however, they soon return, and as I sat down for lunch at 1200 I gave in. I can only hope that the old adage 'what goes up must come down' isn't reversed again. Lunch, a lovely pasta, improves the feeling slightly. Then, before you knew it, I was being briefed for the introductory scuba dive - free though essentially pointless if you didn't go down afterwards. Once here though, there is little point in not doing it! So, after a little panic where I couldn't blow the water out of the mouthpiece, I and the others in the group - four Norwegians - were ready to go.

It was a singular experience, sinking deeper and deeper to see the coral further down, yet still alive. Touched one of the moving corals, picked up by the guide. We see a Moray Eel! Long, quite tall and thin, hiding in amongst the coral low down. Fantastic! Quite rare to see, apparently. After one wobble, everything is fine and by the end, just under half an hour later, it is quite relaxed and moving nicely. Apparently at one point I kicked the mask off the guy behind! Then, slowly, with our vests inflated again by the guide, we are above water. A wonderful experience.

Now the boat moves, so I lie down on the sofa 'downstairs' in the main cabin and shut my eyes, feeling a little delicate. 1530: a new location, a different coral, more snorkelling - different this time, the coral much closer to the surface, and I sometimes fewl as if I am falling into it. Followed some heavily blue fish around for a while. Seem to get cold quicker this time, exit at 1620 then shower before retiring again to the sofa. Drift in and out of consciousness (this is particularly bad sea sickness I suspect) as the boat rocks. I couldn't have been a private radio DJ.

Dinner - curry - then out onto the deck watching some little sharks swimming around, the biggests perhaps two and a half feet in length. Others go for a night dive ($85) but I don't, instead eavesdropping on a lesson going on about the ins and outs of decompression. Four dives a day maximum, don't get drunk the night before. At depth of 18m, the maximum time underwater is 50 minutes - at 39m it is just five. This is all to do with the amount of Nitrogen being taken into the body. This is why they stop 5m below the surface before surfacing - to breathe and remove the nitrogen from your system and get more oxygen back in. The deeper you go, the higher the pressure is and the more nitrogen goes into the body. Not good - feeling queasy again! Talk about suffering for an experience. Makes a Whitsundays trip look a little unlikely.