I've recently returned from a diving trip to St. Abbs; in fact, I've just finished cleaning my kit and stowing it away. Although I'm now exhausted and my hands look like I've been juggling with broken bottles, I had a great time. From the outset, I have never really discovered why I enjoy SCUBA diving so much, but I guess it's something to do with the change of perspective. I spend most of my week staring at a computer screen, so to be able to escape to an environment that alienates the silicon chip brings a sense of relief that can only be truly appreciated when you spend your days locked in a constant battle of wits with what amounts to a particularly stubborn, jumped-up, opinionated calculator.

Fish are odd creatures, really, but they're not as strange as jellyfish. Jellyfish worry me. After all, what exactly do they do? Whenever I see them, they're just oozing around in the water. They don't indulge in high-spirited play, they don't dart about effortlessly. They do sting you if you're not careful, but I don't call that a reason for existence. However, and this is the important part, for all their floppy, oozy, meandering appearance they can still break the four-minute mile if it means they could pop up by your right shoulder and scare the pants off you.

But for all the jellyfish, SCUBA diving is still an intensely enjoyable experience. Remembering the visions of underwater walls tens of metres high, covered with starfish and colourful sponge-like growths; remembering the crowds of hungry wrasse circling round you carefully; remembering the columns of air bubbles dancing delicately to the surface of the water - all of these thoughts preserve a tranquil slice of paradise that I can escape to during the working day.

At least I'm safe until they perfect the underwater laptop.