Sunday River is a ski resort in the northeastern United States, located in Newry, Maine, One of Maine's largest and most visited ski resorts, its vertical drop of 2,340 feet (713 m) is the second largest in Maine (after Sugarloaf) and the sixth largest in New England. The resort features 139 trails across eight interconnected mountain peaks, and is serviced by a network of 19 lifts.

In 1960, Sunday River had four ski runs, a t-bar lift and a rope-tow lift, lift fees were US$3.50 (or $1 for tow-rope), and the ski season was from approximately December 20 to April 15.

Sunday River and its sister resort Sugarloaf have been operated by Boyne Resorts since being sold by American Skiing Company in 2007 for a combined $77 million. The resort's land has been owned by CNL Lifestyle, then Och-Ziff Capital Management, and leased back to Boyne.

In 2018, Boyne Resorts completed the purchase of all leased ski areas in New England from CNL Lifestyle.

Vertical Descent of the mountain, as well as the vertical descent from the chairlifts.

Sunday River is home to the Gould Academy Competition Program for skiing. The program is for junior skiers in Alpine skiing (slalom, giant slalom, super G and downhill), Freestyle skiing (moguls and freeride), and Snowboarding (halfpipe, slopestyle, Slalom, Giant Slalom and boardercross), and runs from mid November through March.

Sunday River hosted the NCAA skiing championships in 1976, 1999, and 2009. It is home to the Dumont Cup, created by Simon Dumont.

In 2009, Simon Dumont wanted to create an opportunity for young and rising skiers to gain exposure and decided to host it at his home mountain, Sunday River in Newry, Maine. Six Dumont Cups later, the success stories of amateur skiers like Nick Geopper and Gus Kenworthy winning the Dumont Cup and stepping into the pro scene has help achieve Simon's vision. The event was eventually officially discontinued in 2016, and the last competition held in March 2015 on the T72 terrain park.