Littlehampton Lifeboat is warning people heading to East Beach during the hot weather to take extra care in the water.
The South remains under a yellow heat-health alert, with temperatures expected to stay high and many families likely to head to the coast to cool off.
But swimmers are being urged not to enter the water in the first zone in front of the coastguard tower, near the river. Crews say there are very dangerous currents close to the river mouth which can quickly overwhelm even strong and experienced swimmers.
Littlehampton Lifeboat says it has already had several call-outs this season to people who have been caught out by the current and found themselves struggling in the water.
Anyone visiting East Beach is being encouraged to speak to RNLI lifeguards if they are unsure where it is safe to swim. Lifeguards are on duty at Littlehampton East Beach from 10am to 6pm throughout the summer.
The warning comes as the latest spell of warm weather brings more people to beaches, rivers and open water locations across Sussex and Hampshire.
People are also being reminded of the risk of cold-water shock. Even on a hot day, sea, river and lake water can be much colder than the air temperature. Entering cold water suddenly can cause people to gasp, breathe rapidly, panic or lose control of their movement.
Safety advice is to enter the water slowly where it is safe to do so, avoid jumping straight in, and never swim alone. Anyone who gets into trouble should try to float on their back, keep their airway clear, and call for help.
If you see someone struggling in the sea, call 999 and ask for the Coastguard.
Littlehampton Lifeboat says people should enjoy the beach, but respect the water, follow lifeguard advice and avoid areas known to have strong currents.
Get the latest BREAKING NEWS for the SOUTH on your phone by downloading the V2 RADIO APP today! Read with ease, no annoying pop-up ads.
V2VOUCHERS.CO.UK is offering half-price deals on a wide range of experiences across the South, from meals out at local restaurants to tickets for some of the region’s biggest events.
WEATHER: Heat-health alert as temperatures climb across the South
Two new NHS dental clinics planned for Portsmouth
Community grants in Mid Sussex
Sussex urged to take part in Big Butterfly Count
University of Chichester marks impact of dementia learning programme
Permanent repairs to Worthing Pier to begin this summer
VIDEO: Free course for young motorcyclists launched by police in Hampshire and the Isle of Wight
Hosepipe ban to be introduced in Hampshire and Isle of Wight
Tribute paid to a “beautiful, loved boy” from Southampton
ID appeal following robbery in Littlehampton
On Air