Head to Rock Creek State Park and rent a pontoon from the Rock Creek Marina for an afternoon on the lake. Fishing and hiking opportunities are also available.
If golf is more your style, enjoy a round of golf at the Grinnell College Golf Course or Oakland Acres Golf Club. Lake Nyanza offers a free 18-hole disc golf course large enough to host families and friends with ease, with discs available for purchase at Bikes to You.
If it's late spring or summer, visit the local waterpark, Grinnell Mutual Family Aquatic Center, for some fun in the sun. Alternatively, bike along one of Grinnell's famous gravel bike trails. If it's winter, consider cross-country skiing or sledding with friends!
Finally, check what events are happening at Central Park. Grinnell hosts live bands on Thursdays throughout the summer for its Music in the Park series, and the Farmer's Market takes place every Thursday and Sunday during the season as well.
And if the Iowa weather isn't conducive to outdoor activities, check the sports schedule and see if you can catch a game of Grinnell College basketball. Both the men's and women's teams have earned national attention for the fast-paced, high-scoring games - and admission to all college sporting events is free!