Aquanauts exit Tektite I in 1969. The Tektite program was the first nationally sponsored effort to place scientists in the sea to live.

Experts discuss the fascinating, and daring, history of underwater habitats. Speakers are Ian Koblick, president and chairman of MRDF and a pioneer of undersea living and Dr. Neil T. Monney, who served as director of ocean engineering at the U.S. Naval Academy for 11 years. The episode also features Bob Barth, a former U.S. Navy diver and veteran of the Navy’s well-known SEALAB program. The episode is sponsored by the Atlantic Rangers Scuba Club.

The Oct. 16 episode addresses how underwater training helps prepare astronauts for space exploration through programs such as the NASA Extreme Environment Mission Operations (NEEMO) project. In the underwater image, an engineering crew diver simulates anchoring to an asteroid surface. The artist’s concept image shows how an astronaut might use a similar process to anchor to an asteroid. Photos courtesy of NASA.

How do astronauts learn how to land on an asteroid? They practice under the sea. Astronauts Buzz Aldrin and Mike Gernhardt discuss how the undersea environment has helped astronauts train for missions beyond the atmosphere. They highlight how undersea simulations will help astronauts prepare for journeys to asteroids and to Mars.

Aldrin, the second person to walk on the moon during the Apollo 11 mission in 1969, pioneered underwater training techniques. Gernhardt, manager of the environmental physiology laboratory at the Johnson Space Center in Houston, has logged more than 43 days in space, including four spacewalks.

The Oct. 16 episode is sponsored by the Sun Chaser Project.

The invasion of the lionfish is one of the topics covered during the Oct. 23 broadcast of Classroom Under the Sea. Lad Akins, director of special projects for the Reef Environmental Education Foundation (REEF), shows a lionfish.

One of the most destructive forces in the ocean today is a fish. One of the most misunderstood fish in the ocean is known for its destructive force.

The lionfish and the shark are the topics of this week's episode. Graham Maddocks, president and founder of the Ocean Support Foundation, said in a 2013 interview with CNN that the lionfish infestation is "probably the worst environmental disaster the Atlantic will ever face." Lad Akins, director of special projects for the Reef Environmental Education Foundation (REEF), discusses the lionfish invasion and how scientists are fighting it. Dr. Jose Castro with the National Oceanic and Atmospheric Administration shares his expertise on sharks.

Wyland’s “Dolphin Vision” and the photography of Stephen Frink are two examples of how the ocean inspires art, the topic for the Oct. 30 episode of Classroom Under the Sea.

The ocean inspires writers, artists and photographers. Marine life artist Wyland and underwater photographer Stephen Frink share how the ocean influences their work and how they use art to show the fragility of the oceans.

USA Today once called Wyland “the Marine Michelangelo.” It is estimated that more than 1 billion people view Wyland’s murals each year. Frink is among the world’s most frequently published underwater photographers and is a Canon Explorer of Light, an elite designation for photographers.

Marine archaeologists not only find shipwrecks such as the steam freighter Northern Light, located off Key Largo on the Florida Keys, but they also use science to reconstruct lost history. Marine Archaeology is the topic of the Nov. 6 episode of Classroom Under the Sea. Photograph courtesy of the National Oceanic and Atmospheric Administration/Department of Commerce. Tane Casserley, NOAA/MONITOR NMS.

Human history is written on the ocean floor. How do explorers and scientists find cultural resources beneath the sea, preserve them, and reconstruct stories lost in the depths of the ocean? Corey Malcom, director of archaeology for the Mel Fisher Maritime Heritage Society, and marine archaeologist Timmy Gambin from the University of Malta discuss the fascinating field of marine archaeology. The episode features ancient Roman and Greek vessels discovered by archaeologists.

The Nov. 6 episode is sponsored by Jules' Undersea Lodge.

Remotely Operated Vehicles, or ROVS, are one of the tools used by ocean explorers. In this 2005 image, the (ROV) Hercules searches for deep sea fauna. Photograph courtesy of the National Oceanic and Atmospheric Administration/Department of Commerce.

The oceans remain a source for fascinating discoveries. Best-selling author Richard Hyman and filmmaker Andy Pruna Sr. shares tales from their decades of experience in ocean exploration. Hyman's book Frogmen is his personal account of his journeys with Jacques Cousteau and the crew of the Calypso, a minesweeper that Cousteau converted into a research vessel. Pruna Sr. was one of 40 Navy aquanauts trained to live and work in the ocean as part of the Navy's Man in the Sea program. His documentaries on wildlife have received widespread acclaim.

The episode also features an interview with Craig McLean with the National Oceanic and Atmospheric Administration (NOAA) and guest Chelsea Wegner, a Sea Grant Fellow with NOAA and a University of South Carolina graduate with a master's in marine science.

Classroom Under the Sea host Bruce Cantrell surveys a reef, one of many ways recreational divers can contribute to conservation.

You do not have to be a marine scientist to help conserve the oceans. Recreational divers can help protect underwater resources, too. In this episode, diving experts share how recreational divers can contribute to ocean conservation, and they discuss how anyone, in any state, can become certified divers through the Professional Association of Diving Instructors (PADI), which sponsored the episode. The episode features Lisa Rollins from popular The Weather Channel show "Catching Hell," Sarah Egner, assistant director of MarineLab (www.marinelab.org), and an interview with Amy Slate, owner of Amoray Dive Resort (www.amoray.com).

The decline of coral formations will be the topic of the Nov. 13 episode of Classroom Under the Sea. The photo shows coral polyps on Molasses Reef in the Florida Keys National Marine Sanctuary. Photo by Brent Deuel, courtesy of the National Oceanic and Atmospheric Administration/Department of Commerce.

Approximately 50-80 percent of the large coral population in the Caribbean has died in the past 40 years. Dr. David Vaughan from the Mote Marine Laboratory & Aquarium and Ken Nedimyer, president of the Coral Restoration Foundation, discuss the devastation of coral reefs and what is being done to preserve coral formations.

This episode is sponsored by the United Way of Roane County.

During the final episode of Classroom Under the Sea on Dec. 11, aquanauts Bruce Cantrell and Jessica Fain put their experience in perspective.

As they end their 73-day underwater mission, Roane State's Bruce Cantrell and Jessica Fain put Classroom Under the Sea in perspective. What did they learn? Where do we go from here? What can you do to help with ocean conservation?