Find a pot with a steaming rack that is large enough to hold the lobsters comfortably. A 4-5 gallon pot should work for about 8 pounds of lobster. Fill the pot with about 2-inches of water. Add sea salt to the water and bring the water to a boil.
Put your live lobsters onto the steamer rack and place the lid on top. It should take 12 to 15 minutes to cook the lobsters through (12 minutes for 1.5-pound lobster and 15 for one that is closer to 2 pounds). It's easiest if all of your lobsters are roughly the same size!
Remove lobsters to a platter to cool. Serve with melted butter and lemon slices.
Notes
Cooked lobsters will turn bright red.
Cooked lobster meat will be white instead of translucent.
Some say you can check doneness by pulling on an antenna and if it comes out easily then it's done. (This does not always work for me. I just time 12 to 15 minutes for the size indicated and they turn out great!).
1 pound lobsters should be done in about 8 minutes.
2½ pound lobsters (if you should be so lucky) take about 20 minutes.
Nutritional information includes the lobster only.