I always liked the acronym, SCRU, the best, I thought, in the federal government. It stood for the Submerged Cultural Resources Unit, a collection of National Park Service world-class divers stationed in Santa Fe, New Mexico, who also happened to be professional archaeologists, anthropologists, and illustrators.

I got to know them well as I supervised the division and dived a couple times with them toward the end of my career with the National Park Service. The chief of the unit was Dan Lenihan, author of the fascinating book, Submerged: Adventures of America's Most Elite Underwater Archeology Team. The book is well worth the attention of Traveler readers.

The obvious question is what are divers of SCRU doing stationed in Santa Fe? It is the offspring of the National Reservoir Inundation Study (NRIS), This was a 1970s program designed to measure the impact of dam construction on archeology.

For four years, Mr. Lenihan and his team dived in almost every reservoir in the Southwest, laying a foundation for a permanent underwater archeology program in the National Park Service. During those years, the team began to develop diving protocols for deep water diving, diving in limited visibility areas, diving at altitude (which the Navy diving tables did not address) and decompression procedures.

Submerged is a fascinating look at a world that few inhabit. Readers accompany the team as it finds and documents ship wrecks in Biscayne National Park, Dry Tortugas National Park, and Isle Royale National Park. This last park presented special challenges to the SCRU team. Mr. Lenihan documents the effects of Lake Superior's icy cold water on a diver's mental and physical abilities. He even reports slush in the mouths of divers, a fact that makes a "free flow" of air through a malfunctioning regulator a life-threatening emergency as the diver's lips are too numb to properly seat the back up regulator.

We learn of the diver's reverence for the sailors of the USS Arizona and their vow to never swim inside the ship as it is the final resting place for so many. We dive in the English Channel to document the Confederate war ship, the CSS Alabama, sunk in 1864 in an engagement that was watched by crowds from the shore. Here the strong currents in the Channel and the extreme depth of the Alabama make the reading exciting.

Mr. Lenihan recounts that at their decompression stop, they breathed pure oxygen from mouthpieces tied to a line. Since there was nothing to hold on to, divers hung on by their teeth while the current extended them out like flags, flapping in the breeze. If they let go, they could not come to the surface until the allotted decompression time had elapsed. As Mr. Lenihan notes, by that time they could drift halfway to Ireland.

The team dives in the Aleutians to document a Japanese sub lost in WWII, in Bikini at the request of the Department of Energy to determine if diving was safe on the ships sunk in the harbor to test the efficacy of nuclear weapons on naval resources, and off the coast of Mexico to document the United States brig Somers, sunk in 1846 during the Mexican-American War. In 1842 on the Somers, the son of the incumbent secretary of war was hung for treason. This later served as the inspiration for Herman Melville's Billy Budd.

All these projects are recounted in Mr. Lenihan's highly developed story-telling style. He is obviously proud of what SCRU has done and wants to share the team's stories with the reader. He praises the members of the team while often discounting his own contributions to their successes. I found his writing very engaging.