Travel · Destinations · 6 min read

Anchuruli Tunnel and Waterfall: Idukki's Hidden Wonder

At the end of a quiet road near Kattappana, a perfectly round tunnel opens onto the Idukki reservoir, and in the rains a waterfall roars from its mouth. The story of the Anchuruli tunnel, the five hills that gave it its name, and how to visit safely.

By GK Global, Adimali, Munnar · Trails & Tales by GK

The road ends at the water's edge. Before you lies the Idukki reservoir, still and green, ringed by forested hills, and set into the rock beside it is a great round hole: the mouth of a tunnel, perfectly circular, more than 7 m across, disappearing into darkness. Stand in front of it and you can feel the cool air breathing out of the hill. In the dry season you can see, far away, a tiny point of light at its other end. In the monsoon, a river of white water thunders out of it and pours down into the reservoir. This is Anchuruli, one of the most unusual and surreal places in Idukki.

The tunnel

When the Idukki hydroelectric project was built in the 1970s, engineers needed more water to fill the great reservoir behind the arch dam. They built a small dam on the Erattayar river near Kattappana and drilled a tunnel straight through the hill of Kalyanathandu to carry its water into the reservoir. The tunnel was built for the Kerala State Electricity Board by Pailey Pillai (also spelled Pyli Pilla), a contractor from Kolenchery; work began in March 1974 and was completed in January 1980. It runs 3.77 km (2.34 miles) through solid rock from the Erattayar forebay to the Idukki reservoir, with a circular section about 7.3 m across. (Popular tourism sources often give 5.5 km, but 3.77 km is the length in the KSEB's specifications for the Erattayar diversion.) It is owned by the Kerala State Electricity Board. It was hard, dangerous work, and about 22 workers lost their lives during its construction.

(Read more about Kerala's hydroelectric projects in the Pallivasal story.)

The waterfall

When heavy rain falls on the Erattayar catchment, water rushes through the tunnel and bursts from its mouth as a roaring, frothing waterfall that tumbles about 15 m into the reservoir. It is a spectacular, deafening sight, and on monsoon weekends thousands of visitors come to see it. In the dry months, especially April and May, the tunnel runs dry, and you can look into its dark, echoing mouth.

The five hills

The name Anchuruli means "five urulis", the round-bottomed vessels used in Kerala kitchens. It comes from five rounded hills in the reservoir that, when the water level falls, rise from the lake like upturned vessels. Around them, the reservoir is fringed with forest, and in the quiet hours you may see kingfishers, egrets and cormorants over the water.

On film

Anchuruli's atmospheric setting has drawn filmmakers; it became widely known after it appeared in the Malayalam film Iyobinte Pusthakam (2014), and it remains a favourite spot for photographers.

Visit safely

• Do not enter the tunnel. Entry is officially prohibited, even when it looks dry: the floor is slippery and uneven, there is no lighting or safety system, and water can come through without warning when it rains upstream.
• Do not climb down to the waterfall or the water's edge below the tunnel mouth, and never swim in the reservoir.
• Watch the falls from a safe distance, especially in the monsoon.
• Respect the warning boards and fences, and keep children close.

Best time to visit

• June to November: the monsoon and post-monsoon months bring the waterfall to life and fill the reservoir.
• December to March: calm, clear weather, with the five hills emerging as the water drops.
• April and May: the tunnel is usually dry; you may see light at its far end.
• Early mornings and late afternoons are quiet and beautiful.

How to get there

• By road: about 10 km from Kattappana; Kumily is about 40 km away, Kalvari Mount about 20 km, and Munnar about 70 km.
• By rail: the nearest major stations are Kottayam and Ettumanoor (about 90 km).
• By air: Cochin International Airport is about 130 km away.

(Read also: Kalvari Mount and the waterfalls of Idukki.)