Add the shrimp to a small pot and cover with water then season with salt. Turn the heat to high and cook the shrimp while stirring until they have just turned pink. Drain from the water and cool.
Cut the shrimp into bite sized pieces saving 4-6 whole pieces depending on how many cocktails you are making.
Add the cut shrimp, tomato, onion, cucumber, celery, jalapeno, and cilantro to a large mixing bowl and mix well.
Mix together the ketchup, clam juice and lime juice juice then and to the shrimp bowl and mix well.
Season the shrimp cocktail with sea salt and fresh ground pepper and add a few drops of hot sauce if you are using it.
Add the diced avocado and mix gently, then cover the bowl and chill for an hour or so.