Add cucumber, pineapple, frozen banana, light coconut milk, water, lime zest, lime juice, greens, and ice cubes to a blender and blend on high until creamy and smooth, scraping down sides as needed.
For a thicker smoothie, add more ice. For a thinner smoothie, add more liquid of choice. Taste and adjust flavor as needed, adding more lime juice or zest for acidity/brightness, banana or pineapple for sweetness, coconut milk for creaminess, and greens for more intense green color.
Serve immediately. Leftovers will keep covered in the refrigerator up to 24 hours, though best when fresh.
* For creamier smoothie, use canned light coconut milk. For a lighter smoothie, use coconut beverage from a carton or sub coconut water! *For added protein, add 1-2 Tbsp (amount as original recipe is written // adjust if altering batch size) hemp seeds or chia seeds, or your favorite neutral or vanilla-flavored protein powder. I don't have any favorite powders at the moment, but Vega Viva Vanilla is the closest thing to palatable I've found. *Nutrition information is a rough estimate.