The Kenai River originates from Kenai Lake in the Kenai Mountains and flows 82 miles westward through the Kenai Peninsula before emptying into Cook Inlet near the towns of Kenai and Soldotna. This glacially-fed river displays a striking turquoise color in its upper reaches, where sediment from Kenai Lake has settled, leaving crystalline waters that gradually transition to a silty green downstream. The river passes through the Kenai National Wildlife Refuge and forms 7-mile-long Skilak Lake midway through its course, creating distinct sections with dramatically different character.

Paddlers divide the Kenai into three main sections. The Upper Kenai (17.3 miles from Kenai Lake to Skilak Lake) is designated drift-only with no motorized craft permitted, offering Class I-II water punctuated by the Kenai Canyon—a 2-4 mile stretch of Class III to III+ whitewater through sheer-walled gorges. This section includes popular rapids like Fisherman's Bend and flows through pristine wilderness where gravel bars, log jams, and braided channels demand attention. The Middle Kenai (19.5 miles from Skilak Lake to the Sterling Highway Bridge in Soldotna) drops at 5.4 feet per mile and features Naptowne Rapids, a challenging Class III-IV section that requires experienced boat handling. The Lower Kenai (21 miles from Soldotna to Cook Inlet) mellows considerably, with the final 12 miles influenced by tidal fluctuations and current speeds dropping below 2 knots.

Peak paddling season runs from June through August, though spring offers solitude before fishing crowds arrive. Wildlife encounters are common throughout: brown and black bears feed along banks during salmon runs, moose wade through shallows, bald eagles perch in cottonwoods and spruce forests, and harbor seals occasionally venture upstream. The river supports world-famous salmon runs including sockeye, king, silver, and pink salmon, which attract massive fishing pressure, particularly near the Russian River confluence where thousands of anglers congregate.

Access is excellent via the Sterling Highway, with multiple launch sites including Cooper Landing (Kenai Lake outlet), Jim's Landing, Lower Skilak Lake Campground, Bing's Landing, and numerous points in Soldotna. Cooper Landing serves as the primary staging area for upper river trips, situated 2.5 hours south of Anchorage. Multi-day expeditions of 4-5 days can cover the entire river system, though most paddlers tackle individual sections as day trips.

Regulations are strict: the Upper Kenai prohibits motors year-round, specific bank closures apply July 1-August 15, and single-hook artificial lure restrictions exist in various zones. Hazards include cold water temperatures (often below 40°F), sudden weather changes on Skilak Lake that can generate dangerous whitecaps, submerged rocks throughout the middle section, and powerful hydraulics at major rapids. The canyon sections offer no realistic portage options once committed.