Both involve water resistance, buoyancy, and density of water and air. Therefore, I would expect that the lift up of your foot would be easy but putting your foot down would be the most difficult. Lifting an object is easier bc of buoyancy force. Although, apart the object must be buoyant itself for that to work. I don't really get that bc buoyancy would still be there based on the general principles involved. I'm guessing the force wouldn't overcome the resistance possibly making it only somewhat easier.