As Hanuman proceeded to Lanka, the celestials were curious to know how determined Hanuman was. So they asked Surasa, the mother of the Nagas, to transform herself, so that she would look like a fearful demon, with tusks, and red eyes.
She stopped Hanuman and said that she had a boon, and that in fulfilment of that boon, she was going to eat him. Hanuman said that if she was prepared to wait until his task of meeting Sita had been accomplished, then he would willingly enter her mouth and become her food. But Surasa said that she would not allow him to pass. She opened her mouth wide to swallow him, but he grew in size. The wider she opened her mouth, the larger he became in size, elaborated Goda Venkateswara Sastrigal, in a discourse. Then Hanuman suddenly reduced his size, and he entered quickly into her gaping mouth and slipped out. But this was not the only hurdle Hanuman had to surmount. A demoness called Simhika began to tug at Hanuman’s shadow, and this slowed him down in his flight towards Lanka. She opened her mouth wide, to swallow Hanuman. Hanuman shrank himself, flew into her mouth, tore her apart, and then went on his way.
In Lanka, a demoness, called Lankini beat Hanuman. Hanuman retaliated by beating her very gently, and Lankini was killed by that slap. In the throes of death, she recalled a prediction, which said that she would be killed by a monkey and that when that happened it was a signal that there would be danger to the demons. Now that prophecy had come true. Thus Hanuman surmounted all the hurdles in his path, and attained his goal of meeting Sita.
