I follow Vinny in scraping my tanks along the ragged edge of the hole

I follow Vinny in, scraping my tanks along the ragged edge of the hole. Maths questions? It slowly dawns on me that he wants me to answer these questions He told me about this before the dive I go through them as fast as I can Vinny times me I take 35 seconds He then shows me some pieces of coloured cloth. There’s sand at the bottom and we come to a gentle stop, resting on our knees. I notice that with each breath I am sucking in vast quantities of air – my lungs labouring as they force it through my regulator.Vinny points at me and hands me a slate with a series of maths questions Initially, I am confused.

We follow a fixed line down to the Khram – an ex-US landing craft, re-commissioned by the Thai Navy and then sold and sunk to provide a dive attraction. There are four divers in total – Vinny, myself, Troy (an Australian also taking the Advanced course, and my appointed dive buddy) and Scot (an experienced American diver).The Khram looms into view, its superstructure fused with thousands of barnacles, and swarms of tropical fish darting around the rusting hull. Air consumption, caused by the extra compression that occurs at this depth, is extremely rapid and can cause breathing problems. Buoyancy, essential to maintaining control when diving, can also be difficult. The extra compression also has another major effect – nitrogen narcosis.

As the air breathed gets thicker with the pressure, the concentration of nitrogen increases. The resultant narcosis can turn the diver into a pubescent teenager: inappropriate behaviour, undue anxiety, euphoria, and short attention span In any other situation this would be amusing. In 30m of water it can be deadly.Theory never matches practice but as we begin the dive at least I know what to expect. In true PADI fashion it begins with an explanatory video and a textbook. In order to make my deep and navigation dives – the first day’s focus – I must complete two knowledge reviews.The book is an illuminating read Diving to 30m-plus is a whole new ball game. There are two requisite dives (a navigation dive and a deep dive to 30m) and three elective dives (chosen from a range of 35 electives that includes everything from wreck diving to underwater photography).Unfortunately, for those who don’t like studying, the course doesn’t begin in the water. “We’ll be descending to a depth of 30m, to the edge of the Khram, an artificial wreck, where I’ll be taking you through some simple tests.”The best thing about the Advanced course is that you do most of your learning in the water.

A string of islands – part of an archipelago just off Thailand’s eastern seaboard near Pattaya – cut into the horizon, green woodlands contrasting with the deep blue skies and shimmering turquoise seas. The boat is filled with neatly stacked racks of cylindrical dive-tanks. Several wetsuit-clad figures are moving around, checking equipment, connecting the dive-tanks to their BCDs (buoyancy control devices) and loading the rigs onto their backs. I finish sunning myself and begin to do the same.”This will be the first dive of your PADI Advanced course,” says my instructor, Vinny, a 48-year-old German who works for Seafari, a Pattaya-based dive centre. “Only advanced divers on this trip,” would be the announcement from the dive centre. Later, when the boats returned, I’d listen in awe to the tales of sunken vessels and enormous fish.
Any basic scuba qualification (in my case a PADI Open Water) allows the diver to descend no deeper than 18m (59ft).