Before diving, people apply spit or commercial defog solution to the inside of their masks to keep them from fogging. But why does it work? A client asked me this recently, and my answer was, "I have no idea, good question!" I imagine a majority of divers do not know the answer either.

To understand why spit keeps a mask from fogging, it is important to know why a mask fogs up in the first place.

A foggy mask ruins an entire dive, destroying your view of fish and coral, and impeding communication between divers. It can also be dangerous.  A diver distracted by a foggy mask can lose track of his buoyancy or his surroundings.

The good news is that it's possible to prevent any mask from fogging. However, new masks and used masks must be treated in different ways.

With tentacles up to three metres long and covered with stinging cells, it’s better not to get too close to the Lion’s Mane jellyfish. It’s body can be 2 metres across, making it one of the largest species of jellyfish.

The tentacles are arranged in eight bunches, with each bunch containing over 100 tentacles. The oldest tentacles are often coloured dark red. They have a very severe sting that can produce blisters, irritation and muscular cramp and may even affect respiratory and heart function. Fragments of tentacles, left on buoy ropes for example, retain their stinging power.

SCUBA divers underestimate the amount of life in heavily-fished areas, a study suggests.

Scientists from Australia compared fish counts by SCUBA divers—who produce noisy bubbles—and divers using silent rebreathers. They found little difference in counts between the two in Marine Protected Areas (MPAs), where the fish weren’t frightened of the divers. In more heavily fished areas though, the bubble-free divers recorded 48% more species and up to 260% greater fish abundance than the SCUBA divers.

'Rare' Civil War Shipwreck Discovered Off North Carolina Coast (ABC News)

Maritime archaeologists and researchers in North Carolina recently discovered one of the most significant shipwrecks found off the East Coast in recent years.

During a routine sonar assessment of known wrecks off the seaside town of Oak Island in North Carolina on Feb. 27, researchers and archaeologists stumbled upon the well-preserved wreckage of a blockade runner steamer from the Civil War, according to Billy Ray Morris, North Carolina's deputy state archaeologist-underwater and director of the North Carolina Department of Natural and Cultural Resources' Underwater Archaeology branch.

"This finding is incredibly exciting because it's so intact," Morris told ABC News. "The sonar image shows almost the entire vessel. That's very rare."

The iron-hulled vessel, about 225-feet long, is likely over 150 years old and is the first mid-19th century wreck to be found in the area in decades, Morris said.

He explained that the vessel was a blockade runner for the Confederacy during the Civil War. Blockade runners were "speedy steamers" used to get around Union war fleets, which sought to cut off the Confederacy from overseas trade.

"These were some of the most sophisticated ships of their day, comparable to the high-speed cigarette boats that modern-day drug smugglers might use now," Morris said.

He added the runners often contained war materials for the Confederate army and luxury items -- including "cases of wine, Paris fashion and nice books" -- which sold for a lot of money at the southern docks.

Three blockade runners are known to have been lost in the area: the Agnes E. Fry, Spunkie and Georgianna McCaw, Morris said.

Based on the ship's size and several parts missing from the vessel, Morris believes the wreck is likely the Agnes E. Fry, he said.

"The Fry has the best story, too," he added. "The owner, Thomas Fry, had the ship renamed for the wife. Thomas was also an interesting character. He was later killed while running a blockade in Cuba, where he was helping to supply guns to Cuban rebels."

Morris said he and his team will try diving down to see the shipwreck tomorrow to do further research and confirm the ship's identity.