Once my eyes adjusted underwater, I realised I was surrounded by cuttlefish – and they didn't seem bothered in the slightest to have a human watching their most intimate moments. With vibrantly pulsating rainbows of purple, orange, turquoise and pink and tentacles everywhere, it took me some time to make sense of this cephalopod foreplay, as cuttlefish have more than a few mating tricks up their tentacles.