I'm sure it varies depending on time of year, but the lagoon water and the ocean water were quite warm when we were there in late September. To my knowledge, Rainbow Reef is kept at a cold temperature year round due to the species living in it. It was noticeably colder than the ocean/lagoon water when we were there. Certainly still doable, but good to know in advance!Yes, the water is cold but so is the water in the cove beach area. The Pacific is cold