David Clarence Koskenmaki

David Clarence Koskenmaki passed away peacefully on March 6th, 2026 in Altadena, California, after a 12-year battle with Parkinson’s disease. He was 81 years old.

David was a second-generation American, born in Herman, Michigan on December 29, 1944. David’s love of nature began as a child in the Michigan woods, where his family lived in a house his father built. David’s father was a copper miner and logger, and his mother, a nurse, taught him about nature - animals, and the names of plants and where they grew. When he was seven they moved to Butte, Montana, where he grew up camping and fishing every weekend. He soon developed an interest in other activities - rock climbing, hiking, skiing, bicycling, running, rafting, canoeing, sailing, and archery. A true outdoorsman, David was adept at finding his way using a compass and trail map while exploring and photographing Montana’s many different terrains. During his life, he climbed numerous mountains and peaks including Devil’s Tower, portaged through the Boundary Waters, completed 15 marathons, and rafted through the Grand Canyon three times. Most impressive was his 2006 hike from Mexico to Canada on the Pacific Coast Trail, where he earned the nickname “Super Dave” from other hikers along the way. When not communing with nature, he spent time on the Ham radio, reading and studying astronomy, and playing jazz and classical piano.

As an adult, David chose a career in theoretical metallurgy and physics. He received his Bachelor of Science degree in Metallurgy in 1967 from Montana College of Mineral Science and Technology, his Master of Science in Materials Science in 1970 from Northwestern University, and his PhD in Metallurgy from Iowa State University in 1973. After graduation, he worked for the Armco Steel Corporation from 1973 to 1977 and at 3M from 1978 until 1999. David preferred working in the laboratory to management and held 37 patents for products he designed. He was talented on the domestic front as well, building both an underground sauna and a freestanding garage in his Minnesota home, while taking care of any remodeling issues including electrical rewiring, roofing, plumbing, or auto mechanics. He also generously shared his time and skills in helping others with repairs and projects.

David met his wife, Rosalie Maggio, in Chicago on a sailing trip on Lake Michigan. They were married December 28th, 1968.

David was the embodiment of Finnish Sisu, which means stoic determination, tenacity of purpose, and resilience. Through example, he taught his children to work hard and be kind, and his legacy will live on in his family and friends.

He is survived by his children Liz Koskenmaki (Anthony Thompson), Katie Koskenmaki (Jason Middleton), and Matt Koskenmaki (Nora Terry Koskenmaki); also, his grandchildren, Zoe Koskenmaki, Margot Middleton, and Oliver Koskenmaki; and his siblings, Joyce Koskenmaki, Carl Koskimaki, Frank Koskimaki, and Kathy Carlson. He was preceded in death by his wife, Rosalie Maggio, and his parents, Jean and Dave Koskimaki.

A celebration of life will follow at a later date. In honor of David, the family welcomes donations to raise funds and awareness for Parkinson’s disease through the Michael J. Fox Foundation. https://give.michaeljfox.org/fundraiser/7110034