Lifeguards have issued a warning to swimmers to be on the look out for a fish which has a sting said to be "as bad as childbirth".
According to the RNLI, weever fish are often found burrowed in the sand in warm weather, mostly when there is a low tide, with their poisonous dorsal spines sticking up.
Wild Swim Wales adds: "If you step on one, you'll know about it! It's said to be as bad as childbirth!"
The warning comes as coastal waters warm following the recent hot weather and people head out on summer holidays around the UK.
You can avoid being stung by the small sand-coloured fish by wearing something on your feet at the beach, or by stamping on the ground, which should encourage the fish to move.
Advice for those who do get stung is to plunge your foot into the hottest water you can bear for 30 minutes without burning yourself.
That should then draw the poison out. Failing that, you should call 999.
Signs you have been stung include puncture marks, swelling and red skin. Most lifeguard stations have facilities to help should you come across one.