In 1970, operating out of the port of Mersing, Leaney lead dozens of diving expeditions out into the South China Sea islands off Malaya's east coast. Exploring principally around the islands Pulau Dayang, Aur, Tioman,and Permangil, his expeditions did some of the very early recording of the effect of the Crown of Thorns starfish on coral reefs in that area.
In 1971, prior to the rise of international diving tourism, Leaney led an expedition dive team to the Perhentian Islands off the north east Malay coast, and then another to the Indian Ocean, diving the atolls of the Maldive Islands. In 1972, after diving trips to Australia and New Zealand, he conducted a survey on behalf of the late King Hussein of Jordan, on the feasibility of establishing a dive center in the Red Sea port of Aquaba, Jordan. During the 1970's he traveled extensively working with divers and instructors in England, Malta, Saudi Arabia and Oman.
In 1980 Leaney relocated to Malibu, Southern California, where he worked in the music industry. He started to pursue his interest in diving history, and throughout the 1980's compiled an extensive diving library and a collection of historical antique equipment. His archives currently provide reference research material for diving historians, and items from his collection are on display at various museums. In 1992, this interest in history lead to Leaney to co-found the Historical Diving Society-USA, (HDS-USA) with Skip Dunham. The inaugural meeting featured a mix of recreational, military and commercial divers and the Society continues to provide an educational forum for these separate, but connected, groups to learn about their joint history. Initially formed as a chapter of the British HDS, the Society evolved into an American non-profit corporation. During its 20 year existence Leaney has worn the hats of Chairman, President and Executive Director, and under his guidance the Society has grown from a few dozen members to over 2,700 in 44 countries. It is internationally affiliated with similar organizations.
To guide the new Society, Leaney helped establish and develop an international Advisory Board of divers, who had distinguished themselves in their chosen fields. Under his guidance the HDS-USA Advisory Board has continued to grow in stature along with the Society. Members include Sylvia Earle, Hans and Lotte Hass, Scott Carpenter, Sir John Rawlins, James Cameron, Bev Morgan, Lad Handelman, Dr. Christian Lambertsen, Zale Parry, Andre Galerne, Ernie Brooks, David Doubilet and many others. A listing of the full HDS-USA Advisory Board can be found at the head of the home page.
In 1993 Leaney founded Historical Diver Magazine, (later renamed to The Journal of Diving History), America's first, and only, publication devoted to all aspects of diving history. As founding publisher and editor he introduced various columns, including the "Women Pioneers in Diving" column written by former Skin Diver Magazine editor Bonnie Cardone. He also printed numerous historical articles translated from foreign language, including Russian, French and German that had never before been published in America.
Through his research, Leaney has written numerous articles that have appeared in several international publications, and is the historical columnist for PADI's Undersea Journal. He has lectured on the subject of diving history at seminars in France, Canada, Mexico, England and America. Numerous authors reference Leaney’s research and he has acted as a consultant for The History Channel, The B.B.C., The Discovery Channel, United States Navy and other organizations.
During his international travels he has assisted in strengthening the ties between America and divers many other countries who wished to record their own nations diving history. Leaney's work with the Musee du Scaphandre in Espalion and the World Festival of Underwater Images in Antibes, helped lay the foundation for the formation of HDS France. He was also instrumental in forming Societies in Russia, Asia, Germany, Canada, Mexico and South East Australia and Pacific.
As the American representative of Austrian diving pioneers, Professor Hans Hass and Lotte Hass, Leaney worked with Ed Stetson and orchestrated their return to American in 1998 for a film festival in their honour. A stellar cast comprising of Zale Parry, Al Giddings, Stan Waterman, Ernie Brooks, Al Tillman, Sylvia Earle, Phil Nuytten, Howard and Michele Hall, Emory Kristof, Bev Morgan and Andy Rechnitzer who participated in the event. "It was the finest tribute occasion I have ever attended," said Stan Waterman.
Working again with Ed Stetson, Leaney became the co-organizer of the annual HDS Great White Shark Fund Raiser at Guadalupe Island, Mexico, in which members get to dive with pioneer divers like Rodney Fox, David Doubilet, Bob Meistrell, Bev Morgan, Ernie Brooks and Stan Waterman.
Leaney has served the HDS since its founding, contributing thousands of volunteer hours in numerous areas of the Society's administration. Fund-raising and sponsorship programs created and introduced by Leaney have risen in excess of $1,000,000 for the Society. He has played a vital role in many of the major developments in the Society's history, including negotiating the strategic HDS affiliations with the Association of Diving Contractors International (ADCI), the Diving Equipment & Marketing Association (DEMA), the Professional Association of Diving Instructors (PADI), Divers Alert Network (DAN), the Beneath The Sea (BTS) non-profit corporation, and the Santa Barbara Maritime Museum (SBMM).
Leaney serves, or has served, on the Board of Directors of The International Scuba Diving Hall of Fame, The Commercial Diving Hall of Fame, the Academy of Underwater Arts and Sciences, the Santa Barbara Maritime Museum, the Historical Diving Society USA, and other educational organizations.
Among his awards are the Academy of Underwater Arts and Sciences NOGI Award for Education, the Beneath the Sea Diver of the Year Award for Service, The Wyland Foundation ICON Award, The Historical Diving Society E.R. Cross Award, the British Historical Diving Society Award, and Honourary Life Time memberships in the Historical Societies of Russia, Canada and South East Asia, Pacific.
Leaney is an inductee in The International Scuba Diving Hall of Fame, a Fellow of the Explorers Club, a Fellow of the Academy of Underwater Arts and Sciences and, by the nomination of Dr. C. Lambertsen, a Lifetime Member of the U.D.T. Seal Association.