Floating on the water.
No interactions present.
I know these little insects well as I studied them for a Uni project way back - they have an inbuilt circatidal rhythm and start heading up the shore to hide in crevices before the tide reaches them (usually.... these look like they got caught out, though they float really well thanks to hydrophobic hairs all over them) and will continue this behaviour pretty much on a 12.5 hour for a weeks or so even when kept 100 miles from the coast in controlled conditions. The study was later published after more detailed work by my supervisor and others http://www.zoo.cam.ac.uk/zoostaff/foster/PDFs/McMeechan_et_al_2000_JMBA.pdf I even helped a film crew record this beahviour for a BBC wildlife series.
Nick Upton, naturalist and photographer.
I'm pretty sure these were in a tiny sand pool in shadow of Rhossili cliffs. It's always puzzled me why some are such a bright blue.
Lat/Lng: 51.5693, -4.2962
OS grid ref: SS409881