A short paddle around the headland from Big Lagoon, Small Lagoon is reached through a low cave entrance that you usually need to duck through. Inside, the water is even more brilliantly green than at its bigger neighbour, and the cliff walls feel closer overhead. There are two small caves you can swim into off the back of the lagoon if the tide is right.
Bring goggles — the swimming is much of the point here — and avoid going at very low tide, when the entrance can be impassable. Snorkelling along the outer cliff walls turns up reef fish and the occasional small turtle.