Indonesia's Bekudo Bono Festival Rides a Six-Metre River Wave

Every November the village of Teluk Meranti in Riau, on the Indonesian island of Sumatra, throws a festival for a wave. It's the Bono, a tidal bore on the Kampar River, and this year's Festival Bekudo Bono runs from 11 to 14 November. Entry is free.

Indonesia's tourism board explains how it happens. The Kampar's two big branches meet near the estuary and the river funnels out into a wide mouth. At high tide the sea pushes in against the current, and the shape of the river squeezes that push into a wall of water that can travel more than 60km upriver. Indonesia Travel says the Bono moves at around 40km an hour with a loud roar, and can rise to between four and six metres, sometimes curling into barrels that surfers love.

Locals have a more wary relationship with it. The same page says many people in the area are frightened when the Bono arrives, linking it to the spirits of the Seven Ghosts, and plenty of boats have sunk after being caught in it.

The festival leans into both sides. According to the event listing there's a Bekudo Bono race and Bono surfing, alongside traditional dance, local music, folk games, a bazaar for small local businesses and camping. It's rooted in Malay tradition, including the Semah ceremony held for safety on the water.

Getting there takes some effort. Teluk Meranti is reached through Pekanbaru, the provincial capital, and then four to seven hours by road, or a speedboat from Pangkalan Kerinci.

Best to watch from the bank if you've only ever surfed a pool.