Montana's most remarkable lakes span from the massive 191.5-square-mile Flathead Lake to remote wilderness puddles accessible only by tire-destroying dirt roads. Whether you're seeking Instagram-worthy shots of Wild Goose Island or hoping to land a 30-pound chinook salmon, the state's diverse water bodies offer everything from lakeside luxury resorts to primitive campgrounds where grizzlies outnumber humans.
Essential planning info you actually need
Before you load up the car and head for Montana's pristine waters, there's some crucial 2025 information that could make or break your trip. The biggest change affecting lake visits in Glacier National Park is the new timed-entry vehicle reservation system, which sounds more complicated than it actually is.
If you're planning to visit Lake McDonald via Going-to-the-Sun Road's west entrance, you'll need a vehicle reservation through Recreation.gov between June 13 and September 28 from 7 AM to 3 PM. The good news? It's only $2 for the reservation plus your regular $35 park pass that's good for seven days. The even better news for spontaneous travelers… St. Mary Lake on the eastern side requires absolutely no reservation, making it your best bet for last-minute Glacier lake adventures.
When to actually jump in the water
Let's be honest about Montana lake swimming: most of these waters are teeth-chatteringly cold. Peak season runs July through August, when "warm" is a relative term. Lake McDonald reaches a positively tropical 70°F in August (making it Glacier's warmest lake), while most others hover around the "are you kidding me" temperature of 50°F year-round. If you're from Florida, maybe stick to looking at the pretty water. For ice fishing enthusiasts, the season typically runs 90 days, with Fort Peck's 2025 season kicking off January 19.
The fishing license situation
Here's where things get refreshingly simple. You need a Montana fishing license everywhere except inside Glacier National Park boundaries, where no license is required at all. The 2024-2025 regulations brought some changes, including mandatory single-point hooks throughout the Flathead Lake and Flathead River system. Bull trout are catch-and-release only statewide, so practice your gentle release technique. If you're fishing the southern half of Flathead Lake, you'll also need a tribal permit because that portion lies within the Flathead Indian Reservation.
The famous trio everyone talks about
These three lakes dominate Montana tourism brochures for good reason… they're absolutely spectacular and relatively easy to access, though "easy" is doing some heavy lifting here.
Flathead Lake deserves its reputation
At 191.5 square miles with 187.6 miles of shoreline, Flathead Lake claims the title of largest natural freshwater lake west of the Mississippi. The statistics are impressive, sure, but what really matters is that you can actually swim here without immediately regretting your life choices. The water hits a balmy 68°F in August, which feels like a hot tub compared to most Montana lakes.
The lake supports 30 fish species, from native bull trout and westslope cutthroat to introduced lake trout that cruise the depths reaching 370.7 feet. With 13 public boat launches scattered around the shoreline, finding water access isn't the challenge… deciding which stunning spot to launch from is. The five state park units offer 140 campsites ranging from $4 to $34 per night, with Big Arm and West Shore being the most popular and requiring advance reservations.
Wild Horse Island, all 2,160 acres of it, provides day-use boat access only. Yes, there are actually wild horses, along with bighorn sheep and over 500 bird species during migration. It's like a nature documentary you can paddle to.
The lake faced some drama in 2023 when drought conditions dropped water levels 31 inches below full pool, sparking the introduction of the "Fill the Lake Act" by Representative Ryan Zinke. Nothing motivates political action quite like angry boaters and worried tourism officials. Lodging options range from the swanky Flathead Lake Lodge at $300+ per night for an all-inclusive experience, down to budget motels starting around $88 if you don't need your towels folded into swan shapes.
Fort Peck Lake: Where size really matters
Fort Peck might not win any beauty contests against its mountain lake cousins, but with 1,520 miles of shoreline (yes, that exceeds California's entire coastline), it wins everything else. This behemoth holds 18.7 million acre-feet of water behind a Depression-era dam that employed 10,546 workers at its peak construction.
The fishing here borders on absurd. We're talking over 50 fish species, including Montana's only harvestable chinook salmon population where 16 to 30-pounders are caught regularly. Walleye in the 8 to 10-pound range are common enough that locals barely raise an eyebrow. Lake trout exceeding 20 pounds lurk in the 220-foot depths, probably wondering how they ended up in eastern Montana.
Twenty-four concrete boat ramps ensure you'll never have to wait in line, even during tournament season when the Crooked Creek Walleye Tournament brings competitors from across the region. Three full-service marinas at Fort Peck, Hell Creek, and Rock Creek provide everything from gas to guide services. Hell Creek State Park offers 71 campsites with 44 electrical hookups, because roughing it doesn't mean your RV's air conditioning has to suffer.
The surrounding Charles M. Russell National Wildlife Refuge encompasses 1.1 million acres where you might spot mule deer, elk, bighorn sheep, or even discover fossils in the paleontologically significant formations. The dam itself generates 185.25 megawatts of hydroelectric power, which is probably more than your teenager uses charging their phone.
Lake McDonald: Glacier's accessible showpiece
Stretching 10 miles through a glacially carved valley, Lake McDonald reaches depths of 472 feet while maintaining the kind of crystal clarity that makes you understand why people become poets. This is Glacier's largest lake and, miracle of miracles, actually achievable swimming temperatures of 70°F in August.
The historic Lake McDonald Lodge operates from May 16 to October 2, offering 82 rooms starting around $200 nightly in Swiss chalet-style buildings dating to 1913-1914. The lodge maintains its historic character by providing limited WiFi and absolutely no televisions, forcing you to actually look at the spectacular scenery or, heaven forbid, talk to your travel companions.
The Glacier Park Boat Company operates historic wooden tour boats including the DeSmet, built in 1930 and the park's only double-decker vessel. For the more independently minded, rental kayaks and paddleboards let you explore at your own pace, which usually means stopping every five minutes for another photo.
Thirteen hiking trails radiate from the lake area:
- Trail of the Cedars (0.7 miles, wheelchair accessible)
- Mount Brown Lookout (5.2 miles, 4,325 feet elevation gain)
- Hidden Lake (varies depending on your fitness level)
- Multiple backcountry connections
Apgar Campground's 194 sites make it the park's largest camping facility, requiring reservations through Recreation.gov with a six-month booking window that fills faster than a teenager's phone storage. No fishing license is required within park boundaries, but native species like cutthroat and bull trout are strictly catch-and-release, so plan your fish photos accordingly.
Hidden gems worth the effort
Beyond the famous lakes lie waters that reward those willing to venture off the beaten path, where "beaten path" sometimes means "any path at all."
Tally Lake plunges into mystery
Montana's deepest natural lake drops to disputed depths of 445 to 495 feet (nobody can agree because it's really, really deep). Located nine miles down a dirt road from Highway 93 near Whitefish, Tally Lake rewards adventurous souls with 1,211 acres of pristine mountain water surrounded by old-growth Western Larch and Douglas Fir forests.
The water here is peculiar… dark and tannic, it actually absorbs heat despite the extreme depth, making it warmer in late summer than typical clear mountain lakes. The USFS-managed campground offers 39 sites from mid-May through October, with 21 reservable and 17 first-come sites. Fair warning: there's absolutely no cell service here, which is either a blessing or a curse depending on your relationship with your inbox.
The campground rents kayaks, paddleboards, and canoes for exploring waters that local legend claims harbor giant sturgeon in the mysterious depths. Nobody's proven this yet, but nobody's disproven it either. Cliff jumping attracts thrill-seekers to various spots around the lake, though we recommend checking the depth first unless you enjoy surprise underwater obstacles.
Fishing targets cutthroat and rainbow trout, brook trout, northern pike, and kokanee salmon. The extreme depth makes shore fishing about as effective as fishing in your bathtub, so boat trolling is your best bet. The Tally Lake Overlook Trail climbs 1.2 miles with 200 feet of elevation gain to panoramic views that'll make your Instagram followers hate you just a little bit.
St. Mary Lake frames perfection
Wild Goose Island rising from St. Mary Lake creates one of America's most photographed mountain scenes, and for once, the photos don't lie. This 9.9-mile-long lake maintains water temperatures below 50°F year-round (swimming is for penguins and Canadians), with winter ice reaching four feet thick across its 3,923-acre surface.
Here's the brilliant part: unlike the western entrances, St. Mary requires no vehicle reservations for 2025, providing easier access to this glacial masterpiece. Multiple roadside pullouts mean you can capture that perfect Wild Goose Island shot without hiking anywhere, though the 2.4-mile round-trip trail to St. Mary and Virginia Falls offers spectacular views for those willing to walk.
Rising Sun Motor Inn operates from June 8 through September 14 with 72 units that preserve their 1940s character by having no televisions or air conditioning. It's like time travel, but with better mattresses. The Glacier Park Boat Company offers 1.5-hour tours for $22 per adult, highlighting waterfalls and Sexton Glacier while navigating waters where mountain winds can transform calm conditions to dangerous whitecaps faster than you can say "maybe we should head back."
St. Mary Campground provides 148 sites as the park's largest eastern facility. Rising Sun's facilities include Two Dog Flats Grill (yes, that's really the name), a camp store, and boat launch, providing the eastern side's primary lake services without the crowds of the Going-to-the-Sun corridor.
Holland Lake: Your wilderness gateway
Nestled at 4,050 feet in the Swan Valley, Holland Lake's 413 acres provide a gateway to the Bob Marshall Wilderness while supporting excellent fishing for stocked rainbow trout that occasionally reach 15 pounds. That's not a typo… fifteen pounds of rainbow trout, though catching one requires either skill, luck, or a combination of both fortified by beer.
The historic Holland Lake Lodge, originally built in 1925 and rebuilt after a 1946 fire, currently operates under new ownership with limited group bookings while planning a 2026 public reopening. The 1.6-mile trail to Holland Falls climbs 750 feet through forests to a 50-foot cascade that ranks among Montana's most rewarding short hikes, especially if you define "rewarding" as "there's a waterfall at the end."
The USFS campground's 40 sites include Bay Loop and Larch Loop configurations, running $22 nightly for individual sites. The group area accommodates up to 100 people for $200-350, perfect for family reunions where you need space to avoid that one uncle.
More lakes worth exploring
Seeley Lake anchors year-round recreation along Highway 83, hosting one of western Montana's finest bass fisheries in its 1,031 acres. The newly redesigned Big Larch Campground offers 29 sites with swimming beaches and boat launches. Winter transforms the valley into a Nordic skiing paradise with groomed trails offering 3, 5, 7, and 10-kilometer loops, plus 350 miles of groomed snowmobile trails for those who prefer their winter sports with engines.
Bowman Lake in Glacier requires navigating rough dirt roads from Polebridge, where the century-old mercantile's famous huckleberry bear claws provide the last taste of civilization. The 7-mile-long, 253-foot-deep lake sits in the remote North Fork area, accessible only via roads that challenge even high-clearance vehicles. The reward? Unparalleled solitude in one of Glacier's most pristine settings where grizzlies still outnumber humans on most days.
Making it all happen
Water temperatures vary dramatically between glacial lakes barely reaching 50°F and lower-elevation waters achieving brief swimming comfort. Fort Peck offers everything from tournament fishing to fossil hunting across its massive shoreline, while intimate Holland Lake provides wilderness gateway experiences in just 413 acres.
Download offline maps before visiting remote lakes… seriously, your phone's GPS is useless without cell service, and asking a grizzly bear for directions rarely ends well. Bear safety transcends all locations, with proper food storage mandatory whether you're camping at developed sites or exploring backcountry shores.
Peak season runs July through August when water temperatures become most tolerable, though this coincides with maximum crowds at famous destinations. Glacier's timed-entry system affects lakes differently, with McDonald requiring morning reservations while St. Mary remains freely accessible, making eastern approaches appealing for spontaneous visitors.
Whether you're seeking Instagram-worthy shots of Wild Goose Island, trophy walleye at Fort Peck, or solitude at Bowman, Montana's lakes deliver experiences ranging from family-friendly to genuinely wild. Each reflects the state's spectacular geological diversity and outdoor heritage, reminding us why Montana's official state nickname isn't actually "Big Sky Country" (that's just a saying), but rather "The Treasure State." And these lakes? They're the real treasure.
