From Sampati, the monkeys learned Ravana had taken Sita to Lanka.
"Who among us is strong enough to leap one hundred yojanas over the ocean to Lanka?" asked Angada.
"I can leap ten yojanas," said one of the monkeys, "but no more."
"I can leap twenty," said another.
"Thirty," said another, "but that's all."
Thus they could find no monkey able to reach Lanka to look for Sita there.
Then Jambavan, the king of the bears, spoke up. "There is one among you who can do this, but he has forgotten his own powers," he said. "That monkey is Hanuman."
Inspired by: Valmiki's Ramayana
Notes: This is from Book 4: Kishkindha Kanda, sarga 65.