The other week, UK diver Bill joined a group on a boat heading out on a dive to find a huge school of monster yellowfin barracuda that would often gather when the current was running at a particular site off a tiny Pacific island.
The moon would be full that night and the tide charts looked promising, so everybody was hoping for action.
The other folk on board were an instructor from a local club with six divers in his charge.
After a quick search, the boat captain reported a sighting of what looked like a large mass of marine life on his fish-finder, issued instructions to his guide and dropped the divers into calm, clear water close to the shore.
Loading the boat for the barracuda dive.
The divers swam out across the bay, following the guide. At a certain point, the guide stopped and, gathering the group together, indicated that they were about to emerge from the protection of the bay into the current.
It hit them almost immediately, and swept them away. They found themselves drifting from bommie to bommie at a depth of around 20m.
When the bommies seemed to be large enough to shield them from the flow a little, the guide would indicate that they should tuck in behind, set their current-hooks and hang there for a while, gazing into the blue, hoping that the barracuda would oblige them with a sighting.
After 20 minutes or so, a school of a couple of hundred fish appeared and approached them, before circling around them for a few minutes. All the divers had their cameras out and got some great shots and footage as they hung in the full force of the flow.
This was however always threatening to make them lose their balance on the end of their current-hooks, and caused a little water to leak into their masks and regulators whenever they incautiously turned their head to the side.
As the school of fish moved away, the group unhooked and started to drift again. Bill saw two divers move up in the water column, away from the bottom.
Both had been breathing more heavily than the others, while watching the fish and getting buffeted by the current, and Bill guessed that they might be low on air.
Their instructor did not seem to have noticed, so Bill moved a little closer to them, prepared to lend help if necessary.
He had also seen that the seabed was falling away, and guessed that the bommies below were now at around 25 to 30m. He had no desire to go deeper so late into the dive.
Then another, even larger school of barracuda turned up, swimming around the drifting group, placing the divers at the centre of a fish vortex.
Bill was happy to watch from midwater, finning determinedly against the current to stay with the barracuda.