Few places are great for an event. Even fewer are perfect for a duathlon, but many can be used for a duathlon. This has been that perfect duathlon venue for years, since 1990, it has seen several course and start finish venue changes but always remaing on the island. A flat first and second run using part of the nature path along the airport as well as a paved walking path.
The bike is the reason you come to Grosse ile to race. One complete loop around the island with Canda on the right first, then Riverview and Trenton Michigan on the opposite side bringing you back to the transition area at the city building and airport. Flat on the Canada site rolling on the Michigan side. You will have wind on one side of the island, that much is a guarantee so take advantage when you have it.