St. Maarten/St. Martin is a hilly island; driving around you'll discover numerous lookouts with splendid panoramas of the coast and offshore islets. One main road essentially circumnavigates the island; a detour from Marigot to Cole Bay on the Dutch side hugs the eastern shore of Simpson Bay lagoon and avoids traffic around the airport and bustling Maho area during rush hours.
The island is shaped -- very roughly -- like a boot. The toe at the western point encompasses the French Lowlands (Terres Basses), a tony residential area with several stunning beaches. Following the main road east takes you through Sandy Ground, a strip of land crammed with tour-group-style hotels, restaurants, shops, and beach bars. It's bordered on the north by Baie Nettlé and on the south by Simpson Bay, the Caribbean's largest enclosed body of water. Marigot, the French side's capital, is just over 2km (1 1/4 miles) to the northeast. Ferries depart its harbor for Anguilla. The main route ambles north, with turnoffs west on rutted roads to fine beaches, as well as east to Pic du Paradis (the island's highest peak at 424m/1,400 ft.) before reaching Grand Case, site of the tiny inter-island L'Espérance Airport, and beloved by foodies for its superlative eateries. The highway runs east, with a fork at Mont Vernon. The north turnoff accesses French Cul-de-Sac (embarkation point for ferries to the offshore cays) and a side road to Anse Marcel, home of a marina and the Radisson resort. The other turnoff accesses the beautiful Orient Bay beach, continuing south through the residential Orléans quarter, straddling the Dutch border at Oyster Pond and its marina.
Dawn Beach, site of increased development (and the Westin resort) is the first major strand on the Dutch side. The main highway turns slightly inland and passes the Great Salt Pond on its way to the Dutch capital, Philipsburg, which unfurls along Great Bay. The major cruise ships dock here; there are also several marinas offering boat rentals and excursions. Pointe Blanche forms the very flat heel. From Philipsburg, the highway parallels the south coast, rising and dipping over Cay and Cole Bay Hills. Traffic here in both directions is often dreadful, especially on weekends: the "Caribbean's longest parking lot," as locals joke. Party central begins at Simpson Bay, where the highway officially becomes Airport Road. Marinas, bars, restaurants, timeshare units, casinos, and strip malls line both sides, continuing almost unabated past Princess Juliana International Airport to Maho Beach, another nightlife nirvana. The road passes Mullet Bay and the lively Cupecoy area in the Dutch Lowlands before hitting the French border.