If a woman goes swimming in the sea erev leil tevilah – is there anything that she should be concerned or particular about during her preparation.
1. She must ensure that she cleans herself well of any salt/sand residue after the sea.
2. She should avoid swimming underwater, to ensure that she does not do a full tevilah in the sea (immersion in the sea can be a kosher tevilah, depending on a number of factors), which is kosher bedieved even before nightfall (see Yoreh De’ah 197:5), and would place into question the blessing recited over the final immersion in the mikvah.