The best way to explore Sea Pines is by bike. Bikes can be reserved in advance and delivered/picked up from your house at no charge. For rentals, call (843-785-5470) or email (hello@peddlingpelican.com) Peddling Pelican and mention you're with the Watson-De Groen wedding for a discount.
Savannah is a famous city known for its history and Southern charm. This popular tourist attraction is about an hour drive from Hilton Head and makes for an excellent day trip. The trolley tours (https://www.trolleytours.com/savannah) are a great way to get a feel for the city in a short amount of time.
The most famous golf course on the island and one of the top courses in the US. Make sure to book your tee time well in advance because they fill up quickly. Please note a forecaddie is required on this course. | $$$$
There are several companies that offer in- and off-shore fishing charters. If you're looking for something more laid back, you can always throw out a line in one of the many lagoons in Sea Pines. Just make sure to watch out for alligators. Please note that you must purchase a fishing license.
Hilton Head features several mini golf courses, including Legendary Golf (https://legendarygolfhhi.com) and Pirate's Island Adventure Golf (http://www.piratesislandgolf.com/hilton-head-sc-pirates-island).