How to get rid of crab lice? drown them?

Nope.: They can hold their breath a long time, apparently. Treatment of choice is still Permethrin cream, applied to the area and washed off after 10 minutes. I usually recommend repeating the treatment a couple of days later to be sure.

Treatment: Pubic lice (phthirus pubis) can be treated with otc product like nix (permethrin) or rid. Other options are prescription medications like Malathion (kept on affected area for 8 to 12 hours); invermectin (2 pills – may need to repeated in 10 days); lindane (if you have failed other treatments).