
On the way back to Shiraishi Island, at about 11:00 pm, the phosphorescence in the water was very bright. This photo is looking down at the water from the side of the boat. You don't have to be on a boat to see the phosphorescence, however. You can set it off by throwing a stone into the water from the beach or by just walking in the shallow water--anything that causes the water to stir. But nothing compares to the brightness a boat creates as it plows through the water at a good speed.
Some people go night kayaking to see this phenomenon. It is quite beautiful as each time you put your paddle in the water, it is rewarded with a spray of underwater light. On the island, they call this phosphorescence "umi hotaru" or sea fireflies.