A Newquay lifeboat was launched following reports a paddle boarder had separated from their board near to Porth Island on Sunday.
The crew were paged and tasked to launch the charity's D Class lifeboat at 10.08am.
The lifeboat arrived on scene five minutes later to find a snorkeler in the reported location in no difficulty.
The D class crew and the Coastguard were satisfied after investigating that this was a false alarm with good intent.
A Newquay RNLI Lifeboats spokesperson said: “If you see anything slightly suspicious or encounter a coastal emergency dial 999 and ask for the Coastguard.”