Around 40 teenagers were found drinking and jumping off a dredger into the sea off the coast of Llanelli.
Officers from Dyfed-Powys Police arrived at the scene in Pwll and found the youths drinking and 'tombstoning' off the dredger.
Tombstoning is an act of jumping in a straight, vertical posture into the sea from a high jumping platform.
Officers reminded the group about current social distancing guidance and they left the scene.
A tweet from the force's neighbourhood policing team in Llanelli urged parents and guardians to be aware of where their children are amid the coronavirus pandemic.
It stated: "Moved approx 40 youths off the dredger in Pwll, tombstoning and drinking.
"Do you know where your teenagers are?"
A spokeswoman for Dyfed-Powys Police said: "Police attended on the afternoon of Tuesday, June 2, using the 4E’s approach (engage, explain, educate and enforce), however enforcement was not necessary as they all left having been reminded about social distancing."
At the weekend, officers from South Wales Police found a group of 100 children gathering at a former quarry in Kenfig Hill.
Officers were also called to Brombil Reservoir in Port Talbot, following reports of mass gatherings at the weekend, with one man even refusing to return home.
Earlier this week saw the lockdown eased in Wales, meaning people are now able to arrange to meet others from different households outdoors, ideally within five miles.
In doing this, however, people must still follow social distancing and strict hand hygiene practices to control the spread of the virus.
