A lake has caught me off guard once before. But as a fully grown adult. I jumped in to swim a distance I could comfortably swim in the sea, but the slightly low

A lake has caught me off guard once before. But as a fully grown adult. I jumped in to swim a distance I could comfortably swim in the sea, but the slightly lower buoyancy I had in the lake caught me completely off guard. I was hundreds of meters from the shore when I finally admitted to myself I was exhausted. Made it back fine, but made me much more cautious about swimming in fresh water.