I refuse to drop myself into the open sea unless I have, at the
bare minimum, a mask, snorkel, and fins. I'm too scared to swim in
the open sea without them. 
the other time .. during wakeboarding.. light rain.. so we
stopped for a while .. and it was quite cold up on the surface, so
all of us jumped into the sea to swim .. coz the water's so warm ..
but we're quite close to the boat la.. so not that worried..