ESB is warning the public not to swim in its reservoirs.
It's due to hidden dangers like deep, fast-flowing water and uneven terrain.
This includes reservoirs Carrigadrohid and Inniscara.
The ESB says:
"Given the recent spell of warm weather ahead of the May bank holiday weekend and as we expect to experience improving weather over the coming months, ESB would like to remind the general public of the dangers and potentially serious consequences of swimming in any ESB reservoir."
Martin Stronge, Senior Manager, Hydro Operations said:
"To ensure your safety and the safety of others, always choose safer swimming locations such as swimming pools or beaches with designated lifeguards."