Whale watching around 'Eua runs from approximately June through October, when humpback whales migrate through Tongan waters to breed and give birth. 'Eua has a small advantage over other Tongan whale-watching destinations: the island sits close to the edge of the shallower Tongan platform, meaning whales often pass through deeper water nearby and can be seen from the coast as well as from boats.
The island's guesthouses can arrange whale-watching trips with local boat operators. Because 'Eua is less developed than Vava'u — Tonga's main whale-watching hub — trips here tend to be less crowded and the experience more intimate. Swimming with whales is also possible under Tonga's permit system, though availability depends on the operators and conditions on the day.