Merino is a miracle fabric. Before the days of air conditioning it was not uncommon to see persons who worked in offices wearing woollen jumpers, especially on very hot days.
Back in the day before wetsuits were a cheap throw away item they were so expensive that nearly only professional or semi professional divers could afford them.
The poor people (me) had to make do with other alternatives to keep warm whilst diving (snorkelling, couldn't afford SCUBA gear either) and the best alternative of all was an old woollen jumper, one where the fibres had become a bit matted.
The jumper restricted water movement next to your skin enough to prevent you becoming too cold over an extended period.
This little beauty was worn by the German Kriegsmarine (navy) and is still available. I have one in my kit bag in the last forty years. It is just as brilliant for sailing as it is for horse or motorcycle riding or skiing!
