Descent and submersion is simulated with bubbles that rise across the viewports when the vehicles pass through compressed air released under the hull and waterfalls.
This process usually involves submersion in a brine of vinegar and salt water with herbs and spices, including peppercorns, coriander, dill, and bay leaf.
Instead, diving birds increase their muscle mass, resulting in an overall increase in body mass that reduces the effects of buoyancy and makes submersion easier.
