1. spherical deep-sea vessels designed to carry observers to great ocean depths
Usage: scientific; marine exploration

Examples

• The bathyspheres descended thousands of feet below the ocean surface.
• Early bathyspheres were made of steel and had thick walls to withstand water pressure.
• Scientists used bathyspheres to study deep-sea creatures in their natural habitat.
• The bathyspheres were lowered by cables from ships on the surface.
• Modern submersibles have largely replaced the original bathyspheres.
• Bathyspheres allowed researchers to observe the ocean floor directly for the first time.