I am going to Greece and was wondering if anyone has any thoughts/advice about visiting Hydra. I am going to visit Santorini and Mykonos and have time to visit another island and heard Hydra was nice.
Hydra is well respected and would be a good option. Best done as a separate trek from Athens as compared to Santorini and Mykonos. There are frequent ferries that hit the Saronic Gulf islands almost as commuter ferries. You can also get there from a port on the Peloponessian peninsula (don't recall the name) after visiting Nafplio and Epidaurus.