A pleasant half or full day can be spent exploring the countryside around Ha Tien, with a convenient circular route northwest of town meaning you won’t need to backtrack. This makes an ideal bike ride when the weather is good.
Strike off west along Lam Son. At the end of the road, turn left and continue straight at a small roundabout. A war cemetery serves as a landmark on the right 2.5km from town, and where the road forks, branch left, signposted Nui Den (lighthouse). Follow this road to the coast and along a winding stretch of road with some beautiful views until you reach the entrance to Mui Nai beach (5000đ per person, 1000đ per bike).
A pleasant – if not idyllic – four-hundred-metre curve of sand, shaded by coconut palms and backed by lush green hills, Mui Nai beach offers reasonable swimming in clean, shallow waters. The beach is very popular among Vietnamese, and there are several resorts here, though they’re all overpriced and poorly maintained. The best of the bunch is the Hong Phat (t 077 395 1661; 400,000đ), with reasonable air-conditioned rooms and a restaurant too.
There are a few other restaurants and beachside cafés, so you can kick back and crack open a few crabs while enjoying a fresh coconut juice or a refreshing slice of watermelon.
Leave the beach at the far end and turn left on to the coast road, weaving your way between rice fields, shrimp farms, water buffalo wallowing in ponds and signs reading 'Frontier Area’. You’ll see the 48m-high granite outcrop housing Thach Dong, or Stone Cave, long before you reach it; 3–4km past Mui Nai the road reaches a junction, where a left turn leads to the Cambodian border.
Turn right at this junction and very shortly the road passes a cluster of food stalls that mark the entrance to Thach Dong (daily 6.30am–6pm; 5000đ per person, 1000đ per bike). A monument shaped like a defiant clenched fist stands as a memorial to 130 people killed by Khmer Rouge forces near here in 1978. Beyond this, steps lead up to a cave pagoda that’s home to a colony of bats. Its shrines to Quan Am and Buddha are unremarkable, but balconies hewn from the side of the rock afford great views over the hills, paddy fields and sea below. Look to your right and you’re peering into Cambodia.
From here, continue along the circular road that will bring you after a few kilometres back into Ha Tien.