Had a Hands to Bathe once in the med; I elected to get changed on the casing and was naked but for a towel that was wrapped around me when, with trunks in hand, I was launched into the oggin. I can vouch for it not being that warm - I nearly drowned trying to get my trunks on before climbing out (there were a lot of cameras pointed in my direction - I had no intention of the effect of the cold water on me being recorded for posterity).Saw (but did not participate in) Hands to Bathe in the Med whilst enjoying the hospitality of an S boat. On that occasion, the submarine kept up a very slow speed - for technical reasons, I was told - and no-one went near the back end for what appeared obvious safety reasons.
I certainly had considered taking part, but did not do so for two reasons. Firstly, I didn't have swimming trunks with me, and secondly, because each of the brave participants who leapt into the deep blue Mediterranean emerged spluttering and shrieking words to the effect of:
"F*ck me, it's f*ckin' freezin!"
I'll try and find pictures. It was interesting to note that the Med was over 10,000 feet deep there.