underwater craft

When it was full a sliding door that was in front of them slowly opened and they passed out onto the deck of the underwater craft.

The underwater craft was still coming on, her periscope in the midst of a hail of fire from the steamer's guns.

We saw a crude type of underwater craft moving in this direction, and followed it at a distance.

To cast anchor would have rendered the ship an easy prey to the underwater craft.

Again those two underwater craft, so oddly contrasted, were face to face.