Heat oil in a deep-fryer or large saucepan to 375 degrees F (190 degrees C).
Stir water and 2 tablespoons sea salt together in a bowl until salt is dissolved. Place potato slices in water.
Transfer 2 handfuls of potatoes using tongs from water to hot oil, cover the pot or fryer, and cook in hot oil until chips are crispy and light brown, 5 to 7 minutes. Transfer to a paper towel-lined plate. Repeat with remaining potatoes.
Place chips in a large bowl and sprinkle remaining salt and pepper over the top; toss to coat.