The lagoon was still and clear, protected from the ocean by a rock wall stacked loosely enough to let the tide through, but high enough to keep the waves out. The wall didn’t look man-made, though it was hard to imagine such a perfect spot occurring by chance.

The lagoon was perhaps fifteen metres across, in an almost-perfect circle. Half of it was sparkle and light and colourful little tropical fish that had run in with the tide playing in shoals. The other half was tucked under the cliff, a cool cave where the slap of water sounded almost wooden and bigger fish drifted lazily. There was a ledge at the back of the cave: just above the water line at high tide, and large enough for two. We could lay there and watch the light throw reflections on the roof, and hear the echo of our breathing and the muted sound of the waves beyond the rock wall.