The Sea Devils attack the island prison and rescue the Master, prompting the Doctor to venture underwater to try and contact them.
Did You Know?
While filming the scene in the minefield, Jon Pertwee
injured his ribs when he dove forward and fell on the sonic screwdriver prop, which was sitting in his breast pocket. See more
Just after the Doctor and Jo enter the mine field and as the Doctor removes his sonic screwdriver a mic can be seen on bottom left of the screen close to the ground. See more
The BBC wish to acknowledge the help given to them by the Royal Navy in the making of this programme See more