Secrets of the deep: Underwater photography competition

Jewel anemones add a splash of colour to the murky depths Photograph: Sally Sharro

A rather glum-looking pike fish swims among the reeds Photograph: Robert Cuss

Who are you? A grey seal looks quizically at his photographer Arthur Kingdon Photograph: Arthur Kingdon

Open wide – a basking shark goes in search of lunch. Unlike its fellow sharks, the basking shark has no teeth. It feeds at or close to the surface with its mouth wide open, filtering plankton Photograph: Cpt JP Trenque

The corkwing wrasse is one of the more unusual and colourful fish found in the UK's seas Photograph: Sally Sharrock

A grey seal takes a leisurely swim Photograph: Martha Tressler

The short-snouted seahorse never fails to fascinate those curious about marine life Photograph: Derek Haslam

Spider crabs scuttle across the sea bed Photograph: Dave Peake