M-Wave, Olympic ice arena in Nagano, Japan

M-Wave is a covered speed skating oval in eastern Nagano, spanning the Asahi and Mamejima districts near the Chikuma River. Its hanging wooden roof, one of the largest of its kind in the world, is built from local larch and shaped to echo the surrounding mountains, giving the building its name. Inside, a 400 m double track encircles a regulation-size ice hockey rink, and two movable stands of 1,210 seats each allow the arena to be reconfigured.

Built in 1996, the facility became the main venue for speed skating during the 1998 Winter Olympics in Nagano. Since then it has remained an important competition and training location for the sport.

The arena's nickname M-Wave comes from its cross-section, shaped like the letter M and meant to evoke the mountains of Shinshu. Since 2008 the National Junior High School Skating Championships have been held here and at Big Hat each year, an event whose economic ripple effect alone is put at 250 million yen. Local promotion Shinshu Pro Wrestling has also staged shows in the arena.

The 400 m oval and the inner ice hockey rink are open from October to March; outside that season the arena hosts sports events, exhibitions and concerts. From Nagano Station's east exit, take the Nagaden bus on routes 82 or 82B and get off at the M-Wave-mae stop. By car it is about five minutes from the Suzaka-Nagano-Higashi interchange of the Joshinetsu Expressway.

The roof structure is distinctively shaped to echo the surrounding mountain ranges and is constructed from local larch wood. This design choice connects the modern sports facility to the natural landscape of the region.