I thought this prompt would be so easy! We'd been having fog for a couple of weeks, and London in grey November mist is very much in the doldrums. But it cleared pretty much at the moment the prompt was posted! So I thought about taking a very dull picture of a not very successful parade of shops... but it was dull. So I went instead for the literal doldrums, where ships can't sail due to lack of wind. Or, in this case, lack of water.