most frequent access from Piraeus please to and island in April

Greek Easter is April 19 when the local population will be traveling so keep that in mind when planning.

Although Hydra maybe isn’t as exotic (or crowded) as Santorini or other islands farther from Athens/Piraeus, it’s a great getaway from the big city, and ferries depart hourly in the morning.

Except when they don’t. We visited Greece the second and third weeks of April 2018. A week before Greek Orthodox Easter, we went from our Athens hotel to Piraeus, expecting to catch the first ferry to Hydra. But the water was so rough that morning that the first ferry got postponed, and we waited for the next ferry, scheduled an hour later. That got cancelled, too, so we split a taxi with another couple, and got driven to another port, where the calmer waters made that ferry possible.

We only had 2 nights on Hydra, but if our schedule had allowed more time, we definitely would have stayed longer. Other islands have flights to reach them - not sure if flying is more reliable or frequent.

A better option for an island that's larger than Hydra and has more to do would be Aegina which even closer to Athens. Lots of ferries throughout the day/evening.

Nothing wrong with Hydra, it's lovely but if you want more choice for what to do then Aegina would be ideal.

April 19 is Greek Easter so factor in your travel plans.

I just suggested Aegina for another query on this topic for March so will just cut & paste that reply here:

Here's a photo album http://www.flickr.com/photos/36264706@N03/sets/72157621604646139/detail/ that is in effect a step-by-step visual of a June daytrip to Aegina. Aside from a swim, all this could be y ours on a sunny day in March ... A particular treat is sitting out on deck on a conventional ferry (do NOT take a hydrofoil) just to enjoy the seascape... all the many vessels, large & small, from huge liners to sleek schooners, with gulls, and waves etc. Much better idea than trying to get to a faraway island like Santorini..

I used this website to find and book ferries, though I learned after I booked one that I could just as easily buy a ticket a day or 2 in advance on the ground, which is what I did for my second (last) ferry. If you are traveling over Easter weekend, you may need to book in advance - many, many Greeks head to their family homes for the holiday.