A man has drowned after rescuing two children playing in the sea at West Wittering Beach in West Sussex.
The 25-year-old went to the aid of the children who got into difficulty after playing with a rubber ring in the sea on Saturday.
Officers said the man - who was not related to the children - managed to get them to safety during the incident, which took place around midday.
A Sussex Police spokesman said: "The male went to the assistance of two children playing in a rubber ring some five metres from the shoreline.
"He managed to get the children to safety but in doing so put himself in danger which sadly resulted in him drowning."
A Solent Coastguard spokesman said: "Their mother was understandably upset that this man had had this accident when he had tried to help them."
He said that an ambulance crew were the first to the scene and a coastguard operation was not launched.
A number of other water-related deaths during the spell of good weather have led to police warnings over the dangers of cooling off in open water.
The body of a 21-year-old man was found on Sunday morning in Caldecotte Lake, Milton Keynes, after he went missing while swimming the day before.
Detective Sergeant Ian Jarvis, the officer in charge of the case, said: "While it might be tempting to swim in lakes and rivers during this hot weather, there are hidden dangers under the water and so we would advise against doing so."
In further incidents, Nicholas Smith, 23, died after getting into difficulty while swimming near a waterfall in Linn Park, Glasgow, and a 22-year-old died while swimming at a disused quarry at Ballykelly, County Kildare, in Ireland. Hussain Mohammed, 15, drowned after jumping into the Thames at Oxford on Friday.