Agree with above poster, if the objective is to say you’ve been to a Greek island, Poros, Aegina & Hydra are the islands you can get to easily from Athens.
May is too cold for swimming in the sea or being on the beach, well for me anyway.

On a good day you can sunbathe, but I agree mid-May seawater temperatures are too cold for swimming. Canadians and Scandinavians may disagree, but even most Scandis wait until late June when their schools break up for the summer.

We visited Delos from Mykonos this past year about the 3rd week of June. We took the first boat over and the last boat back and it still wasn’t enough time to fully explore the site. It’s BIG!

For me, sea temps were chilly even then. But admittedly, I’m used to really warm water 😂.

We are heading back to the Cyclades again this summer but a bit earlier. We’ll be there the final 3 weeks of June. Mykonos again (primarily to visit Delos again), Paros (new for us), and Naxos. Hoping to be able to swim a bit by the time we make it to Naxos which is our family’s fave.

You can t have it all together,if i were you i il spent 3 days in Athens 1 on Meteora nad then i would propably stay in Paros and from there i would visit Mykonos and Naxos.

Are you sure that a day trip from Naxos to Mykonos/Delos will be posible in early May?
I would rather go from ATH via Mykonos to Naxos, may be like this:
Tuesday: ATH ar 14.00, dp 18.00 - Mykonos ar 18.55
Wedneday: Delos, Mykonos
Thursday: Mykonos dp 9.40 - Naxos ar 10.15

Neckervd, what I explained in my Jan 6th, 2019, 10:24 post was that Polos Tours shows Naxos Star scheduled to do the trip to Delos/Mykonos from April 26th, but that it could be cancelled on days when not enough people sign up. Indeed that would be taking a chance. I went on to say: "What I suggest, if you are determined to see Delos, is forget Naxos and go to Mykonos instead."

Thank you all for the useful information! We have definitely eliminated a visit to Meteora this time around. A long train ride for a short visit doesn’t sound fun at all. We are going to ferry to Naxos after Athens -added an extra night in Naxos - so full 3 days there. I contacted the company on Naxos that runs the Delos/Mykonos tour and they will be running at that time ( thank you Heimdall for that info) and I might use the extra day on Naxos to take this tour. Then a quick flight back to Athens - rent a car and head to Nafplio for the last 3 nights. TexasAggie I booked Kavos Boutique Hotel in Naxos based on your accommodation review post.

Your new plan is, IMO, much improved.

Sounds good! I hope the Delos/Mykonos tour runs as scheduled.

Sorry, Heimdall, I overlooked your post 18, indeed!

way better than the first plan