Valmiki Ramayana Sundara Kanda Sarga 1 Shloka 67

तदा then, कपि: vanara, उपरिष्टात् the top, शरीरेण with his body, सागरे in the ocean, अवगाढया reflected, छायया च shadow also, मारुताविष्टा swept by the wind, नौरिव like the ship, आसीत् appeared.

When the vanara was flying in the sky, his shadow reflected in the ocean looked like a ship driven by the wind and sailing on the sea below (as if the lower part of his body was under water and upper part occupied the sky)