Relax, hit the beach, have an ice cream or a beer on the sand. To feel a million miles from Amsterdam or any other city is why you come here.
If you're up for more active pursuits, head to the north end when you get off the bus. Follow the main road by the parking lots to the right; and as it splits, head left into the duinen ("dunes"). The edge of the National Park Zuid-Kennemerland reaches down this way and the entrance named "Parnassia" is about a 15-minute walk from the main beach. You'll see dog-walkers (the road dead-ends into one of the only dog-friendly beaches in summer), bikers, trekkers and even people on horseback, all here to enjoy hundreds of miles of trails through the quiet, sandy scenery.
If you want to extend your time in the park, take Bus 81 back in the direction of Haarlem, this time hopping off at the Kennemerduinen stop. There you'll find the main information center of the park, called Duincentrum De Zandwaaier, where you can find more information on the pine forests, lakes and more trails.