Image from Ops Luyan (flickr)
I think that we all learned in school that a shark's gills don't "pull in" water like the gills of many other fishes. The downshot of this is that a shark has to keep swimming in order to breathe.
Well, it just occurred to me that about the most lucrative place for a shark to hang out would be one of those underwater coves with its own swirling current system. The underwater cliffs would act just like mountains do on land, creating tides and hopefully allowing you to be a lazy shark and still breathe. I'm aware that sharks eat almost continually to maintain energy needed for their constant movement, but hopefully you'd conserve enough energy with this strategy to simplify your day somewhat.
Just another facetious thing I've had my mind on today.
16 minutes ago