Prepare the cucumbers: Peel and chop the cucumbers into small pieces. If using large cucumbers with seeds, scoop out the seeds before chopping.
Blend the ingredients: In a blender, combine cucumbers, Greek yogurt, fresh dill, garlic, lemon juice, olive oil, salt, and pepper. Blend until smooth.
Adjust the consistency: Add cold water gradually until you reach the desired thickness. Blend again.
Chill before serving: Transfer the soup to a bowl and refrigerate for at least 1 hour to allow the flavors to meld.
Garnish and serve: Top with additional dill, a drizzle of olive oil, or croutons. Serve cold.