Drain the canned tuna thoroughly and place it in a medium mixing bowl, flaking it with a fork.
Finely dice the celery, red onion, fresh dill, and fresh parsley.
Slice the Persian cucumbers in half lengthwise and use a small spoon to scoop out the seeds, creating hollow boats.
Roughly chop the scooped-out cucumber centers and add them to the mixing bowl with the tuna.
In a separate small bowl, whisk together the Greek yogurt, olive oil, lemon juice, sea salt, and black pepper until smooth.
Add the dressing, diced celery, onion, herbs, and hemp seeds to the tuna mixture and stir to combine.
Gently fold in the diced avocado, being careful not to mash the pieces.
Spoon the tuna salad mixture generously into the prepared cucumber boats and serve immediately.