Three people had to be rescued after being cut off by the high tide.
RNLI volunteers went to their aid after they became stranded on Worm’s Head, a tidal island off Gower, on Saturday afternoon.
A crew from Horton and Port Eynon Lifeboat was launched at about 16:00 BST after HM Coastguard received an alert.
The RNLI said two people from Ukraine who were working in Swansea and a French student were taken ashore at Rhossili.
They told their rescuers they had misread the tide times, according to the RNLI.
Lifeboat operations manager Lawrie Grove said: “I would remind people when walking on or near the coast to make sure that they check local tide times and plan walks accordingly.
“They should never try to swim or wade to shore when cut off by the tide – it is extremely dangerous.”