Choose a large stockpot and fill it with cold water until the crab is fully submerged. Season generously with coarse sea salt (about ¼ cup per quart of water) and add bay leaves.
If the crab is alive, place it in the pot before turning on the heat. If it’s already dead, wait until the water reaches a rolling boil before adding the crab.
Once the water returns to a rolling boil with the crab inside, cook for about 18–20 minutes for a 2.2–3.3 lb crab.
Turn off the heat and let the crab rest in the cooking water for a few more minutes to deepen the flavor, or transfer it to an ice bath to stop the cooking if you prefer firmer meat.
Serve the crab chilled or at room temperature. To plate, remove the top shell, discard the gills, and pick out the meat from the legs and body. Offer lemon wedges or a simple vinaigrette on the side.