A frequent question in our email inbox is "What sort of exposure protection will I need when I dive in Grand Cayman?"
Unfortunately, this isn't a question that's easily answered. On any dive boat here in the Cayman Islands, you'll see people wearing thick, full-length wetsuits, while other divers are comfortable in a pair of shorts and t-shirt. It really boils down to a person's personal tolerance to cold, and what one considers cold.
A better first question might be, "What sort of water temperature might I expect when I dive Grand Cayman?"
To answer that, we went to our personal dive computers, and looked at a few years worth of temperature data. From here, we discovered something - many of our computers didn't agree on temperature. Even amongst same brands of computer on the same dive. One might read as many as 2-3 degrees different than another. Also temperatures seemed to vary by year. In 2017, the summertime water temperature hit a high of 87 degrees, (according to one dive computer) while in 2018, the summer temp maxed out at 84.
Fortunately, the folks at seatemperature.info have some pretty good historical data on the water temperatures of Grand Cayman, and from them we can get the high, low and average temperature for each month.
Now that we've established the water temperature we are likely to encounter, this still doesn't really address what sort of exposure protection we should be wearing.
This is where your dive log comes into play. Hopefully you've kept notes from your previous dives, and recorded your exposure suit thickness and your comfort level.
If you haven't kept a good log, or simply lack the diving history, then we'd follow these general guidelines:
79 degrees and below - 3mm to 5mm full suit
80 - 84 degrees - 2 mm shorty to dive skin
85 degrees and above - rashguard
A hood is always a good thing to keep in your dive bag, even when going to a temperate environment like the Cayman Islands. It won't take up much room, and can make a large impact on your thermal comfort when you find yourself unexpectedly cold, no matter what else you are wearing.
Happy diving!