People are being warned not to park on beaches after two vehicles became submerged overnight.
Holyhead coastguard said a transit van left at Black Rock Sands, in Porthmadog, was engulfed in the tide.
Meanwhile at Abersoch, in Gwynedd, a parked Land Rover completely disappeared in the water.
The coastguard said parking on the beach had been an ongoing problem at Black Rock Sands.
A spokesperson said the beach was popular with cars, “especially with younger drivers”.
“Nine times out of ten it’s not a problem and they don’t get stuck, but it does happen,” the spokesperson added.
The incident at Abersoch was described as “more unusual”.
“It’s about a metre under the high water. It will become a navigational issue and Abersoch will put a local navigation warning out,” the coastguard said.
“So far no owner has come forward. It will probably end up going to council for recovery unless the owners come forward.”