Fill a large pot approximately three-quarters full of seawater or salted water (2 T of salt per quart of water).
Use about 2½ quarts of water for each lobster.
Bring the water to a boil.
Put in the live lobsters, one at a time, cover and bring the water to a boil again.
Then, lower the heat and simmer -
15 minutes for a 1- to 1¼-pound hard-shell lobster
20 minutes for a 1½-pound hard-shell lobster.
If you have soft shell lobsters, reduce the cooking time by 3 minutes.