Lake Boivin Nature Interpretation Centre is Granby's easiest nature stop, with trails and wetland viewpoints close enough to town to visit without turning it into an expedition. The lake and marsh edges are especially good for birdwatching, quiet walks, and a slower hour between more built-up sights.
The centre is most appealing in mild weather, when the boardwalks and observation points give you time to watch rather than simply pass through. Bring binoculars if you have them; even casual visitors will see more by slowing down.