Mark Green was a crew member on the Chicago Skyline Swim, a 23.5-mile swim in Lake Michigan completed in July 2008 by David Blanke of Austin, Texas (age 48), Chris Layton of Chicago, Illinois (age 49) and Marcia Cleveland of Winnetka, Illinois (age 44). It was a swim from one end of the city of Chicago to the other end, swimming from north to south. Kevin Murphy did a similar swim
The swim took 12 hours, 49 minutes. Marcia Cleveland had these comments afterwards. "Man-o-man, I'm still alive. I'm tired, my left shoulder is aching, I have some major suit rubs, which I've covered with balmex, but I'm very very happy that it worked out so well and we were successful."
Their support crew consisted of two motorized escort boats, two highly experienced kayakers, and three experienced crew volunteers on each boat. Each escort boat was fully equipped with Coast Guard Radios, GPS, and all required emergency equipment. The crew members included Mark Green, Rob Carstens, Max Carstens, Joe Gray, Cooky Donaldson, Dan & Paul, Richard Clifford, Tom Heineman, Heidi Kafka, Liz Kooy, Chip Gray, Jacob Karaca, Peggy Heineman, Laura Slevin Moriarity, Kaari Reierson, Susan Bertram, Kyle Bertram, Kelly Bertram, Kris Rutford, Julia Green, Leslie Blanke, and Robert Zeitner.