The effort, code-named Project Natick, might lead to strands of giant steel tubes linked by fiber optic cables placed on the seafloor. Another possibility would suspend containers shaped like jelly beans beneath the surface to capture the ocean current with turbines that generate electricity.

“When I first heard about this I thought, ‘Water ... electricity, why would you do that?’ ” said Ben Cutler, a Microsoft computer designer who is one of the engineers who worked on the Project Natick system. “But as you think more about it, it actually makes a lot of sense.”

Such a radical idea could run into stumbling blocks, including environmental concerns and unforeseen technical issues. But the Microsoft researchers believe that by mass producing the capsules, they could shorten the deployment time of new data centers from the two years it now takes on land to just 90 days, offering a huge cost advantage.

The underwater server containers could also help make web services work faster. Much of the world’s population now lives in urban centers close to oceans but far away from data centers usually built in out-of-the-way places with lots of room. The ability to place computing power near users lowers the delay, or latency, people experience, which is a big issue for web users.

“For years, the main cloud providers have been seeking sites around the world not only for green energy but which also take advantage of the environment,” said Larry Smarr, a physicist and scientific computing specialist who is director of the California Institute for Telecommunications and Information Technology at the University of California, San Diego.