They seemed to be in the lee of Kinmen. The waves were not as powerful, but they came from many directions and clashed into sudden pyramids of water that just as suddenly collapsed. She just tried to get a bearing on the moon and to keep swimming at all costs. The main thing that she was worried about was being swept out to sea by some unseen current, and indeed when she pulled her head up out of the soup to look at the lights of the island, she got the impression that they were moving sideways at least as fast as forward. She was not much of a nautical person but was enough of a Brit to have absorbed, by osmosis, certain terminology such as "slack water," and she was pretty sure that this was the condition that obtained now: the tide was low, neither incoming nor outgoing, and the water wasn’t moving much. But huge rivers emptied into the sea around Xiamen and their flow had to divert around these islands, and there must be currents associated with that.