One of the best sealers for wood in the bathroom is spar-urethane.
It’s frequently used on submerged wood, like boat hulls. This particular finish is intended to endure the weather on the hardwood poles that hold a boat’s sails, commonly known as the ship’s spars.
Spar urethane was designed to endure difficult circumstances and preserve the ship’s spars since this piece of wood must withstand severe wetness and wind.