Various of us took one of the boats for a trip round the island. Nothing particularly spectacular to be seen form the boat, but once we were back into the lagoon, I went over the side to a patch reef that the boat-master indicated.
First thing to draw my attention was a patch of "Needle Sea Urchins" amongst corals (a species probably in Acropora, but I won't hang for that). Just pretty.
While photographing that, I noticed that, for reasons still unclear, the sea urchins were congregating in particular patches. I don't know why ; I guess that there was something about the substrate that they liked there, but not elsewhere.
A brilliant blue+yellow fish was shoaling in the area.
They particularly liked gathering around a large lobster pot on the reef, but they would also follow each other around over the reef edge too (where I wasn't going to go on ALP, Available Lung Power).
After much hunting around on the net, I identified these as Yellowtail Fusiliers ; they shoaled with Twinstripe Fusiliers, which are only marginally less colourful. (Though this picture doesn't do the colour of the two yellow stripes justice ; I'm going to have to start using the colour balance tool for these duck dives to 3 or 5m.
On my next dive, I spotted this "different" branching coral - which I can't identify.
I've spent more time than I care to think about staring at this sort of assemblage of fossils and sediments ("wackestone to packstone", anyone?), but even so it was very nice to see these environments "in the flesh" as it were.