The island has a land mass of 82 square km. There is a full sized Marina. About 11 ferries a day, price 1500 drx. Fewer in winter. About 16 a day, price 2,000 drx.
Hydrofoils usually stay in port during winter.
Marina and Aegina Town. I suggest boarding a boat bound for the latter as Souvala is a bit industrial and you'll just have to bus to Aegina Town anyway. Best bet is to return to Piraeus for more options. Aegina is a beautiful island with alternating areas of greenery and barren vistas. Most manageable during the week when all the Athenians are back in Athens working.