How often does the boat leave from Manhattan and Stanton island. And how much time is a roundtrip?

Ferry leaves every 30 min to Staten island from Downtown Manhattan and 30 min to Downtown Manhattan from Staten Island. Round trip is 60 mins.

2-3 times per hour, roughly a 60 minute round trip when you include unloading and getting back on for the return trip.

Trip to Staten Island takes about 30 mins and the same while return. Its frequency is good enough 20 mins to 30 mins according to time and the trip is free:) njoy

Every 20 mins during non peak hours. Every 15 minutes during peak hours. A round trip would be 50 minutes.

It's free and 1 hour

Every 30 mins from each side. They have 3 - 4 ferry's so its always on time and never crowded

Every 25 - 30 minutes.

2-3 time per hour about 30 min

Every 30 min