Why do some divers feel cold faster than others in the same water? This chapter breaks down how body type, age, dive profile, and hydration affect heat loss—and how to choose thermal protection that actually works for you.

You already know you’re getting cold on every dive. Now it’s time to understand why and how to control it. From hidden heat loss through breathing to the real science behind wetsuits and neoprene compression, this guide breaks down what actually keeps you warm underwater and how to choose the right thermal protection for tropical diving.