This 1865 drawing of the submarine offers a very simple view of its construction, and was used to sell shares in the submarine company. Image Courtesy of Jim Delgado.

This drawing from Harper’s Weekly shows the popular view of submarines during the Civil War. Image Courtesy of Jim Delgado.

The only surviving original plan of Explorer is this 1864 drawing now in the U.S. National Archives. Image Courtesy of U.S. National Archives.

This LIDAR, or laser scan of Explorer'€™s hull was done by Carlos Velasquez and Doug Devine of Epic Scan in 2004. Image Courtesy of Jim Delgado/Carlos Velasquez, Epic Scan

Explorer, at mid-tide, showing the lower part of the hull as the dropping tide exposes more of the submarine. Photo Credit: Lance Milbrand

The outer shell of Explorer, made of strakes of wrought iron, is succumbing to battering logs, corrosion, and curious visitors walking on it. These holes in the hull are larger than when archaeologists first visited Explorer in 2001. Photo Credit: Lance Milbrand

John McKay's working plans of Explorer guided the team in the 2008 project as they completed documenting the submarine. Photo Credit: Lance Milbrand

As much as 10 feet (3 meters) of tide covers the beach and buries Explorer each day. Photo Credit: Lance Milbrand

Jim Delgado makes notes off Explorer's bow. Photo Credit: Lance Milbrand

This wire rope, wrapped around the submarine'€™s conning tower, is evidence of an early and failed attempt to pull it off the beach. Photo Credit: Lance Milbrand

The Waitt expedition team compares notes in the water off Explorer's stern. Photo Credit: Lance Milbrand

Fritz Hanselmann and Jim Delgado examine the hull. Photo Credit: Lance Milbrand

Jim Delgado points out features of Explorer's construction to Fritz Hanselmann. Photo Credit: Lance Milbrand

The Waitt expedition team prepares to climb inside Explorer. Photo Credit: Lance Milbrand

Fritz Hanselmann, Jim Delgado and John McKay atop Explorer. Photo Credit: Lance Milbrand

Explorer lies in a small cove on Isle San Telmo. Photo Credit: Lance Milbrand

Fritz Hanselmann measures holes worn and battered through Explorer's outer hull. Photo Credit: Lance Milbrand

Archaeologist Fritz Hanselmann, INA Director Clyde Smith and naval architectural draftsman John W. McKay pose off Explorer'€™s bow. Photo Credit: Lance Milbrand

Fritz Hanselmann measures corrosion holes at Explorer'€™s stern. Photo Credit: Lance Milbrand

Fritz Hanselmann measures corrosion holes at Explorer'€™s stern. Photo Credit: Lance Milbrand

The fluctuating tides and waves help batter Explorer apart. Photo Credit: Lance Milbrand

The survey boat Protector passes Explorer while conducting a magnetometer survey. Photo Credit: Lance Milbrand

The survey boat Protector passes Explorer while conducting a magnetometer survey. Photo Credit: Lance Milbrand

A natural pear, plucked from a living oyster wrested from the bottom of the sea by a breath-holding diver. Photo Credit: Lance Milbrand

Local pearl divers from the nearby village of La Esmerelda offer small pearls for sale. Photo Credit: Lance Milbrand

Local pearl divers and their boat. Photo Credit: Lance Milbrand

Wire cable on Explorer'€™s conning tower. Corrosion has melded them together. Photo Credit: Lance Milbrand

The Waitt expedition team on the beach shows the scale of Explorer and its cove. Photo Credit: Lance Milbrand

Marine Biologist Erich Horgan examines marine organisms inside Explorer. Photo Credit: Lance Milbrand

Erich Horgan studies the marine life inside Explorer. Photo Credit: Lance Milbrand

Erich Horgan inspects the compressed air chamber. Photo Credit: Lance Milbrand

Through-hull fittings for Explorer'€™s now-vanished steering mechanism at the stern. Photo Credit: Lance Milbrand

Aerial view of the cove where Explorer lies on the beach. Photo Credit: Lance Milbrand

Isometric lines drawing of Explorer. Image Courtesy of John McKay.

Isometric plan of Explorer. Image Courtesy of John McKay.

Isometric cut-away view of Explorer. Image Courtesy of John McKay.

Isometric sections of Explorer. Image Courtesy of John McKay.