The trail to Motu Reef is about a kilometer south of Lakepa. There's a wide wooden stairway down to the reef from the cave where canoes are stored. A couple of km north of Lakepa, it's a 25-minute walk along an easy-to-follow trail from the trailhead to Vaitafe Spring. Fresh water from a crevice at the foot of a sheer cliff bubbles into a pool where you can swim or snorkel, but the area is accessible only at low tide. You can reef walk here.
At the north end of the island, opposite the church in Mutalau village, is a monument commemorating the arrival of the first Christian missionaries; the first Niuean convert, Peniamina (1846); and Paulo (1849), the first Samoan teacher.
A jeep track across from the monument leads down to Uluvehi Landing, an easy five-minute walk. This was the main landing on the island in the early days; the islanders' sleek outrigger canoes are still stored in caves in the cliffs.
To reach Vaihakea Cave, look for an overgrown trail just 100 meters inland from the streetlight at Uluvehi on the east side of the track. Once you get on the trail, it's only a five-minute walk to this fantastic submerged cave full of fish and coral, but you must climb down a sharp limestone cliff near the trail end. There's excellent swimming and snorkeling at low tide.
The sites mentioned above are only the highlights of Niue; there are many other caves for the avid spelunker to explore with the help of local guides.