Dhigu Thila

At around 400 m long the thila is far too big to circle, so the dive is a traverse: in at one end, along one flank with the reef on your shoulder, and back over the top when gas or time says so. The top comes up to about 8 m and the flanks fall away to about 35 m, which leaves plenty of room to choose a working depth and hold it rather than following every contour down to the bottom.

The overhangs cut along the flank are what slows the swim down, and the small pinnacle off the western side is the one detachable feature on the site — it gets added when the drop point puts you at that end of the ridge. Anything else is a matter of picking which flank to run, since the ridge has two and one dive only covers one of them.

Finish by coming up onto the reef top at about 8 m. That gives a long shallow run over coral with the drop-off still in sight below, and it keeps the safety stop over structure rather than in blue water at the end of a 400 m traverse. It also means the boat has something fixed to look for, which matters on a site where the entry and exit points can be several hundred metres apart.