Now carefully push them into the bottle until the battery compartment rests on the neck of the bottle.

The officers realised that the discs, which are usually made of paper or plastic, had a hidden battery compartment.

That meant seawater flooded into the sub's battery compartment, causing short circuits and an electrical fire.

The battery compartment was sealed and kept shut until mid-afternoon when the outboard battery vent was opened.

As she completed preparations to dive, the forward battery compartment began to flood.