How well do you know the Greek Alphabet????
You don't need to go swimming to find this cache. The original coords aren't correct. To retrieve the cache, you must know the Greek alphabet.
The true coordinates are:
gamma theta beta alpha theta eta beta
zero theta alpha gamma iota eta theta zeta
Example: delta is four, epsilon is five.
Good luck and, as always, be aware of muggles around.
You can check your results with the solution checker.