I left Monemvassia in the afternoon under a wonderful cloudy sky (thanx again, Zeus).
The hidrofoil from inside doesn't seem to go fast, but if you go to the rear, and watch the sea from there, U realize it's bl**dy fast!!
Hidrofoil "Flying Dolphins"
There are 4 buses daily from Athens (5 1/2hours), but the Hidrofoil from Piraeus is faster (4 hours), though more expensive, 30 euros. 1 daily in summer only