I must have been about 10 years old when we spent the holidays in Bergen near the North Sea (Netherlands). One night my father woke me up: “Get up! Put your shoes on, we’ll go to the beach!”
“Why?” did I ask, still very asleep.
“We are going to watch the light of the sea!”

It had been hot and windless all week. Ideal conditions to see sparkling sea turning the beach into a magical place. The waves radiated a blue light. As you moved through the water, blue light rippled around you. And as you walked over the wet sand, a trail of glowing footsteps slowly died out behind  you. Zeevonk, it’s called in Dutch

The light comes from the alga Noctiluca scintillans, which emits a bluish light when moved. Earlier I told about the herrings in my fridge that gave light – probably also caused by the ingestion of these algae while swimming (see Luminescence).

All these years I hoped to one day see that light of the sea again. And last week I did. Not as exuberant as I remember; actually I would have walked right past it if another visitor hadn’t pointed out the puddle that the low tide had left on the beach. But I was just in time, for that night was the last that the phenomenon could be observed. So I am more than happy now, with some fresh memories.