Bring a medium pot of water to a boil and prepare an ice bath in a separate bowl.
Drop the shrimp into the boiling water for 1-2 minutes until just pink and opaque, then immediately transfer to the ice bath to stop the cooking process.
Once cooled, drain the shrimp and chop into bite-sized pieces if they are large.
In a large glass bowl, combine the lime juice, lemon juice, sea salt, black pepper, and extra virgin olive oil.
Add the chopped shrimp, diced cucumber, diced tomato, finely diced red onion, and minced jalapeño to the citrus mixture.
Stir in the fresh cilantro and toss well to ensure everything is coated in the marinade.
Cover and refrigerate for at least 30 minutes to allow the flavors to meld.
Just before serving, gently fold in the diced avocado to maintain its texture and prevent browning.