The quay on St Mary's is the arrival point for most people visiting the Isles of Scilly. This is where the Scillonian III docks after the 2hr 45min sailing from Penzance. Disembarking is fun and you can watch the bags being unloaded and loaded into the smaller inter island boats. From here you can walk or ride straight into Hugh Town and explore St Mary's.
Crossings are regular from March to November. You can get a day passenger ferry or make it a holiday and stay on one for the islands for a great holiday.
Bikes are an additional cost (£32.64 May 2023 price) if you want to take your own. There is bike hire on the islands and none of the islands are particularly big so hire bikes are probably fine.