In a large steam pot with a steamer rack or basket, pour in the beer, apple cider vinegar, and water (if there's enough space without the liquids touching the bottom of the steamer rack). Bring it to a boil.
2 (12 oz ) bottles light lager or ale beer, 2 cups apple cider vinegar, 2 cups water
Once the liquid is boiling, use your tongs to start layering the crabs into the pot but don't pile them on top of each other. Lay them next to each other on the bottom, and once the bottom is covered, season them generously with ⅓ cup of Old Bay Seasoning. Don't be shy with the Old Bay, use more if you want! You really want those crabs covered in those spices.
1 cup Old Bay Seasoning
Use your tongs to place another layer of crabs on top of the crab layer you just seasoned, and once you have a full layer season those crabs generously with Old Bay as well.
Repeat this process for 3-4 layers, we don't want to overcrowd the pot or else the crabs won't steam evenly. Work in batches (or with a second pot, just double the amount of liquid needed)
Cover the pot with its lid and steam the blue crabs for about 20-22 minutes, until the shells are bright orange. If you see some mustard or white albumin starting to push out of them before the allotted time, they're ready to be removed from the pot!
Repeat Steps 2-5 for the rest of the crabs, after removing the batch of steamed crabs from the pot, until all your crabs are steamed and bright orange.