Ile aux Moines is an island in Brittany. It's name IZENAH in breton. It's situated in "Golfe du Morbihan" (Bay of Morbihan), region Morbihan (south of Brittany).
Length 7 km, width 3,5 km, 610 islander
It's the bigger island of the bay, pretty, full of flowers, old stone and amazing landscape, it deserv a walk...
To get the ferry, you need to go in Port-Blanc in city of Baden (15km of Vannes)
From Vannes, you should take the bus line orange (LARMOR-BADEN - VANNES), near train station, but there is few bus by day, so you can also hitchhike: take the bus in Place Republique, line 4 in direction "Mairie Arradon" and stop in station "Le Petit Molac"..you are on the road of Baden! Schedule of bus on = 
In Port-Blanc, you should take the ferry of izenah-croisieres, from 7h to 19h30, there is a ferry each half an hour, 4euros double way.
On the island 3 walkway tour:
The tour of Trec'h (1,8 km one way): discover church Saint-Michel, and from the "Pointe Trech", beautiful view on Arradon and Island of Arz.
The tour of Brouel(2,5 km): discover chapel, fountain, and from the "Pointe of Brouel", a view on Island of Arz.
The Tour of Penhap(4,4 km): discover celtic megalith, view of the bay, thatched cottage, grove, and at 500 meter of Penhap, on the "Pointe de Nioul", a large view on peninsula of Rhuys.
See and print a map here = 
If you want more information, go to the official website of island = 
and if you want discover the other island of the bay, just take a look here = 
Tourism office (in port): 02 97 26 32 45
Mairie: 02 97 26 32 61