Pour water into a large stockpot and add oil, onions, celery, lemons, garlic, ginger, bay leaves, crab boil spice mix, cayenne, black peppercorns and salt. Bring to a boil on high heat then reduce heat and boil for 10 minutes.
Add potatoes and boil for 5 minutes then add crabs and boil for another 15 minutes. After that, add corn and boil for 5 minutes.
Now, add shrimp and boil for 1 minute and turn off heat. Let the mixture stand for 5 minutes in the stockpot.
Take the seafood and vegetables out of the stockpot and transfer them to a serving platter. Use a table knife to crack the shells.
It is recommended to serve them warm but you can serve at room temperature or chilled as well.