In an extra large pot combine butter, bouillon salt and water and bring to a simmer. Add crab legs, shrimp, sausage, garlic cloves, corn and potatoes.
Reduce heat to medium and cover. Cook for 15-20 minutes or until potatoes are fork tender and corn is cooked throughly.
Serve in large bowls with a few ladles of broth and a sprinkle of old bay on top.