Ganvié is a town built entirely on stilts over Lake Nokoué, about 15 km north of Cotonou. It is sometimes called the Venice of Africa, which sets expectations that the reality cannot quite meet — tourism has taken its toll, and arriving from Cotonou you will be surrounded by touts offering to guide you around.
Still, the site is remarkable. During the worst days of the slave trade, the Tofinu people sought refuge on the lake because, according to the religion of the Abomey kingdom, it was forbidden to attack people on the water. In the Tofinu language, Ganvié means "the collectivity of those who found peace at last." The people who settled here built a complete town on stilts — houses, markets, a school — and their descendants still live there.
The best way to visit is by pirogue from the Abomey-Calavi shore. The floating market is most active in the early morning, before the tour groups arrive. Expect to negotiate a price before setting out; going with a reputable guide reduces the hassle considerably.