Trekking to Mt. Rinjani’s Mystifying

Danau Segara Anak is a volcanic lake formed in the caldera of Mount Rinjani on over 2,000 meters above sea level. The lake spans across an area of 11 square kilometers, and reaches depths up to 230 meters. Danau Segara Anak is located on the west side of Mount Rinjani in the village of Lawang Sembalun in Lombok, East Indonesia. The mystifyingly blue colour of the lake gives Segara Anak its name: Small Ocean.

The trek from the Senaru Village, and through the crater to Danau Segara Anak takes two days and a night. 

It begins with a hike through a lush, tropical rainforest, and up the mountain to the rim of the crater. The trek to the Senaru rim is a challenging climb up steep terrain and high cliffs, but the exhaustion is well rewarded by the breathtaking panoramic view of the sun setting over Mount Rinjani, Bali and the Gili Isles on the horizon, and the dazzling blue waters of Segara Anak glistening hundreds of meters below.

The top of the crater is a popular camp site for both foreign and domestic tourists on this journey to spend the night. It is advisable to set a morning alarm so as not to miss the magnificence of dawn from atop Rinjani.From the crater’s rim, it is a sharp descent of about 600 meters to Danau Segara Anak.

Part of Segara Anak

Part of Segara Anak flows down a steep ravine forming one large waterfall and several smaller ones. There are also four natural hot springs in the lake which are said to hold magical healing powers, and many make the climb solely for medicinal purposes.

Despite its high altitudes, taking a dip in the lake is not as cold as one might imagine. 2,010 meters above sea level, the surface water of the lake is unusually warm for such heights, at about 20-22 degrees Celsius—well above the mountain’s “room temperature,” which is about 14-15 degrees Celsius.

Between 2008 and 2009, researchers of Volcanology and Geological Hazard Mitigation as well as UniversiteLibre de Bruxells conducted a geochemical and thermodynamic study on Segara Anak. The tests showed several leaks in the volcanic system of Gunung Baru; the cone in the center of the lake.

These leaks from the magma chamber seep a large supply of hot water into Segara Anak, indicating a direct relationship between volcanic activity and the lake’s high temperature. The geochemical composition of the hot water showed a number of elements such as chloride, sodium, potassium, and sulphate. Although rich in elements, rainwater that enters the lake assists in thinning its chemical content. Segara Anak also maintains excellent circulation, and is therefore not harmful to life.