Choose a pot large enough to hold all the lobsters comfortably; do not crowd them. A 4- to 5-gallon pot can handle 6 to 8 pounds of lobster. Fill with water, allowing 3 quarts of water per 1-1/2 to 2 pounds of lobster. Add sea salt (to taste) to water. Bring the water to a rolling boil. Add the live lobsters one at a time, and start timing immediately. Do not cover. Stir the lobsters halfway through cooking. Boil for 15 minutes. Let the lobsters rest for 5 minutes or so after cooking to allow the meat to absorb some of the moisture in the shell.