Periscope
Fossil
The suffix for "submarine" is "-marine," which means related to the sea or marine environment.
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My choice would be an manatee [See related link for a picture]
The Confederate States most successful submarine was the H L Hunley
The basic ingredients of a submarine sandwich vary according to which type you order. Usually, they include meat, lettuce, cheese, tomato along with other salads and condiments of your choice.
Most submarines were made of steel.
Created by a series of complex processes, submarine canyons continue to be carved by sporadic turbidity currents waterfalls of sand, gravel, and muddy sediments.
A person who drives a submarine is typically referred to as a submariner or a submarine captain, depending on their rank and role. The submariner operates and navigates the submarine, while a captain holds the highest authority on board. Other crew members may also have specific titles related to their duties, such as navigator or engineer.
The Confederacy led in the experimentation with submarines. The most successful was the HL Hunley. This submarine sunk a Union warship however the sinking ship damaged the submarine that also sank.
Multiple-choice questions only work when given the list of possible answers.