I have had 2 moms scuba dive while exclusively breastfeeding (I live in
FL).  One had no problems, diving about 20-30 feet.  I suggested she bf
as close to the dive as possible.  The other woman dove 30-40 feet and
bf before she left on the trip, which meant she had not nursed for
almost 2 hrs before the dive.  She wore a wet suit.  When she got back
into the boat and unzipped her wet suit, she said her milk "exploded"
and she was standing in a large puddle of, not salt water, but white
milk.  She had a big problem of multiple plugged ducts.  No mastitis,
but uncomfortable until she relieved the lumps. She thinks it was the
water pressure because the wet suit fit comfortably.  The other concern
expressed, not hers, but the fellow divers, was if sharks were attracted
by breastmilk.  None appeared during the dive, nor did any baby
porpoises or whales.

Becket Miller, RN,IBCLC
Boca Raton, FL