Ruruidake, Stratovolcano in Kunashir Island, Russia.

Ruruidake is a complex stratovolcano at the northern end of the Dokuchaev Ridge on Kunashir Island, rising to 1,485 metres. Its crater opens to the north, and three wide, deep valleys cut the summit, completely destroying the crater. The valleys narrow downhill and were modified by cirques from a later glaciation; their walls expose typical volcanic structures. The Smirnov volcano is a separate edifice, not a second summit of Ruruidake.

No historical eruptions are known. The summit crater is completely destroyed by three wide, deep valleys formed during the first ice age, later modified by cirques from the next glaciation. Fumarolic activity continues on the western slopes at 150–350 m, and hydrothermal activity occurs near the coast.

The name Rurui comes from Ainu. One reading links "ruru" to the sea, giving "marine", for a volcano whose northwestern foot reaches the Sea of Okhotsk; another reads it as "poison falling as rain", from ru (poison) and rui (to burn, blow, fall like rain).

The summit crater is gone: three wide, deep valleys cut through the top, and their walls expose the volcano's internal structure. The valleys narrow downhill and were reshaped by cirques from a later glaciation. Fumaroles stay active on the western slope between 150 and 350 m above sea level, with hydrothermal activity near the coast.

Smirnov is a separate volcano, not a second summit of Rurui. The name Rurui comes from Ainu: one reading links it to "sea", another to "poison falling as rain". The summit rocks are whitish, altered by fumaroles.