Lake Toba -- Aerial view of the northern tip of Lake Toba with Tongging village in the foreground. This lake of great natural beauty is situated in the centre of north Sumatra. It is twice as large as Lake Geneva (Switzerland) and has an average depth of 1640 feet. Before the district around Lake Toba was opened up by the Dutch, it was considered sacred by the native Batak population and fatal for strangers to approach. The first white man to ranch it was Dr. H. lNeubronner van der Fuuk, in 1863, who was forced to boat a hasty retreat owing to the threatening attitude of the population. March 31, 1950.