Dr Who on the Aqua Planet

The First Doctor, Ian Chesterton and Barbara Wright land on the Aqua planet. Ian notes that he sees fish flying which he thinks is strange. The Doctor explains that the planet has patches of invisible liquid which makes the illusion that the fish are flying. However the water quickly makes its way to the trio, engulfing them. Once in, an Aquamonster attempts to eat Barbara. As Barbara pleads for help, the oceanphere moves, dropping the three back to dry land. Because the Aquamonsters cannot survive outside of their liquid patch the Aquamonster stops attempting to eat Barbara, saving her.