Ganvie is a village in Southern Benin.
Ganvie is a very touristy site and most famous for its stilt village on the large lake that provided a safe hide out from early slave trading. The village is fully equipped for living, most people living from fishing.
A shared taxi from Eglise Saint Michel in Cotonou city center drops you near the embarkation point in Abomey-Calavi for 500 CFA. To visit the stilt village the only way to go is with a tourist tour (in between 3000 and 10000 CFA) as only locals are allowed to take the ordinary boats (200 CFA).
The tourist boat will make a trip through the village, including a restaurant and souvenirshop, lasting for about 2 to 3 hours.
The price for a tour depends on the number of tourists in the boat, so you may want to wait for others to share a boat. A motorized boat costs a bit more than one without an engine. As an example, 1 person for 10000 CFA, with 5 others for 3050 CFA.
Note that the prices for a trip include the price for a guide in French or English. The guides will likely try to make you pay for their service though, even asking for 10000 CFA for giving you a few comments about what you are seeing. In a country where it is often difficult to get change on a 5000 CFA note, obviously, giving 10000 CFA for a few remarks is kinda ridiculous.
The stilt village is well equipped for dealing with tourists, so you can have lunch there.
Near the embarkation point there is a small hotel (hotel chez M) that provides a place to stay and that organizes private tours to the stilt villages where the owner, madam M, lives. If you would be interested in taking their tour, check them first. The son of Madame M is a guide. email@example.com