Samprati, the brother of Jatayu was waiting for Vanara Sena who went in search of Mata Sita. He was waiting for them in Vindhyan range.
From there they came to the northern end of the Indian Ocean.
Vanara Sena was in trouble as they couldn't think of any way to go to Lanka crossing such a big ocean. They didn't have big ships or boats and no time to build the ships.
Then, Jambavana suggested Hanuman had the capacity to cross the ocean and reach Lanka and find Mata Sita. Hanuman leapt from Mahendra mountains and crossing difficulties reached Trikuta Mountain in Lanka.
Lanka existed in the south of Vindhyan Range and in Indian Ocean.