EPA administrator Gina McCarthy calls new rules on greenhouse gas reduction perhaps the most significant in the agency's history.
Fabien Cousteau and a crew of five headed down to the underwater laboratory Aquarius, just off the Florida Keys, on Sunday. He and his team intend to stay submerged until July 2.
The draft proposal from the Environmental Protection Agency has sparked opposition from industry groups who say the changes would be prohibitively expensive.
The proposed Keystone XL pipeline has generated controversy, especially in Nebraska, where opposition to transporting crude from the oil sands of Canada has delayed a national decision on the project.
The Obama administration on Monday will roll out a plan to cut earth-warming pollution from power plants by 30 percent by 2030. The proposal was first reported Sunday by The Wall Street Journal.