Dyfed-Powys Police is appealing for information after two lifebelts were stolen from a disused quarry in Llansawel.
The theft has prompted officers to urge people to remember the dangers of taking life-saving equipment, which might be needed in the event of an emergency.
The force received a report that sometime between June 27, 2017 and July 14, 2017 two life rings were taken from the disused quarry in Pen y Ddinas, Llansawel.
Carmarthenshire Superintendent Gary Mills said: “Theft of a lifesaving device is an extremely serious offence and can have devastating consequences should they need to be used in an emergency and are not available.
“We would urge anyone that sees lifesaving equipment being tampered with to report this to the police straight away.”
Supt Mills has also taken the opportunity to urge people not to swim in quarries ahead of the school summer holidays.
“We would also like to remind people of the dangers of swimming in disused quarries,” he said.
“The water can look inviting, but it is very cold and deep, and even experienced swimmers can suddenly find themselves in difficulty.
“Jumping into the water is also very dangerous as there are rocks, ledges and debris on the quarry floor that can shift and move.”
Anyone with information about the theft of the life rings is asked to contact police by calling 101. If you are Deaf, hard of hearing, or speech impaired, text the non-emergency number on 07811 311 908.