Some of the photos look like they were taken on a mysterious, alien world.
But the images, by local photographer and sea-lover Chris Taylor, reveal a rarely-seen part of Norfolk, an underwater area known as The Gullies, just north of Sheringham lifeboat station.
Mr Taylor snorkelled there on Monday and Tuesday, July 18 and 19, during the heatwave which saw the UK record its highest ever temperature.
"It's a mysterious world hidden from view," he said. "It's incredible. I always think of it like an underwater safari."
Among the multicoloured creatures are bright-orange sponges, blue lobsters, luminous green wrasse and grey crabs with bright red eyes.
The Gullies is an area of rugged chalk walls, some up to 12ft high.
Mr Taylor said the area was "a thriving ecosystem" thanks in part to the local crab and lobster fisherman who in the 1960s prevented commercial fishing on the reef.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here