Preheat grill to medium-high heat and lightly oil grill grate.
While the grill is preheating, mix together turkey, spinach, feta, egg whites, parsley, garlic, sea salt and pepper in a large bowl until well combined. Using your hands, form mixture into 4-5 patties. Cook on preheated grill until no longer pink in the center, about 15 to 20 minutes. Serve immediately.