Heather Massey is a senior lecturer in the Extreme Environments Research Group at the University of Portsmouth. Heather has done extensive work into the human response to cold water, both the physical and mental effects, and her areas of research interest include thermal, altitude and survival physiology.

She's also an amazing ocean swimmer, having swum the English Channel and around Jersey, among other things. And has a podcast called Humans in Extremes, interviewing extraordinary guests who have done extraordinary activities in extreme environmental conditions.

Image from Heather on Twitter.

Songs in this episode - all licensed under a Creative Commons License:

• Ice Cold - Spurb Music