Srimad-Bhagavatam 1.3.22 Purport
...Because Lord Rämacandra was the Personality of Godhead, He exhibited superhuman activities which no human being, including the materially advanced Rävana, could perform. Lord Rämacandra prepared a royal road on the Indian Ocean with stones that floated on the water. The modern scientists have done research in the area of weightlessness, but it is not possible to bring in weightlessness anywhere and everywhere. But because weightlessness is the creation of the Lord by which He can make the gigantic planets fly and float in the air, He made the stones even within this earth to be weightless and prepared a stone bridge on the sea without any supporting pillar. That is the display of the power of God.