Fat Bear Week, the wildly popular online competition celebrating natures biggest success stories, is back at Alaskas Katmai National Park, where hefty brown bears are packing on pounds and battling for internet glory in an annua l salmon-fueled showdown.It's a single-elimination tournament where the public can vote for the bear they believe best exemplifies fatness and success in brown bears.RELATED STORY | Chunk takes Fat Bear Week 2025 crown after years of coming in second placeThe bear with the most votes advances to the next round but only one will be crowned Fat Bear Week champion at the start of October.You can download your Fat Bear Week bracket here. This year's clawed contestants are: 32 Chunk: He's the reigning Fat Bear Week champ! Last year, he came to the river with a broken jaw that experts believe may have been the result of a fight with another bear. But that didn't block his bulk! He returns to the river this year with just as much determination. Will he remain on top? 89 Backpack: His mother and former Fat Bear Week champion, Holly, introduced him to Brooks River when he was a first-year cub in 2006, park officials said. Backpack often climbed onto his mothers back when the pair swam in the river, a habit that inspired his nickname. He hasnt shown much aggression toward his competitors as typical adult male bears do, but hell stand up for himself when necessary. 131 Marshmallow: With each year, this bear has grown larger, and her fishing skills have improved readying her to become a mother. Cubs could be in her future as she appears this September to be proportionally fatter than she has ever been, park officials said. 132 (and her three cubs): This is her Fat Bear Week debut! Shes become one of the largest and most experienced mother bears at Brooks River. Her three spring cubs represent her fourth known litter. She's also mom to 806, another contender this year. 151 Walker: Park officials said that, as a young bear, this guy used to enjoy the company of other bears and could be described as easygoing. Now, he's more willing to challenge others for his spot on the hierarchy at the river. 164 Bucky: He's known for his unique fishing spot. Bucky stands at the edge of the deepest plunge pool, nearly under the cascade of Brooks Falls, catching salmon welling up from the pool below, jumping through the air and falling from above. It's a spot that officials said no other bear has consistently tried to fish. 284 (and her two cubs): She's continuing her family legacy. As a full-grown adult, 284 is known to challenge other bears and sometimes people to protect her personal space or offspring. 428 Studious: As the daughter of the famously defensive and former Fat Bear Week champ, 128 Grazer, she has had access to prime fishing spots at Brooks Falls that are unavailable to most cubs. Will she follow in her mother's footsteps? 610 (and her two cubs): This is her Fat Bear Week debut! She has overcome some adversity since first being spotted at the river. Most bears in Katmai stay with their mothers through two or three summers, but a sudden danger or accident may have led to 610 being separated from her mother at a young age. Now, she's a mom of her own. 620: She is on the cusp of adulthood. Her early life was unique, with her mother and aunt bonding their families together in the summer of 2022, park officials said. It's rare for an adoption scenario in brown bear families. 694: This subadult bear frequently makes time to socialize with others, but play doesnt always take precedence over food for him. He sometimes breaks a play session short to look for a salmon that captures his attention. 806 (and her cub, plus an adopted cub): This is her Fat Bear Week debut! Her adoption of another cub shows her caring nature, but officials point out that she has her limits. Earlier in the summer, she attacked, killed and partly ate 909's spring cub. 901 (and her cub): She has become one of the most prominent and recognizable female bears at Brooks River. But she's had a lot of struggles with the loss of cubs as a young mom. 903 Gully: Believed to be the son of former Fat Bear Week champion 128 Grazer. His nickname comes from his appetite for seagulls, something most of the bears at the river ignore. 909: She is the daughter of former Fat Bear Week champion, 409 Beadnose, and sister to 910. She arrived to the river with two spring cubs, but, sadly, one disappeared and the second cub was killed by 806. She displayed her resilience in the face of loss by navigating the rest of the summer with determination and skill. 910: She's the sister of 909 and the daughter of former Fat Bear Week champion, 409 Beadnose. She can be recognized there by her peculiar and frequent head lifts, a quirk of movement that she does not do anywhere else.Now that the bears and brackets are set, the ferocious game is on.In addition to voting and advocating for their favorite bear, enthusiasts can also watch livestreams from cameras of the bears bulking up from the abundant salmon supply along the Brooks River.Once the contest ends, park officials typically post transformation photos of the contestants showing their visible bulking.Katmai National Park is home to some of the largest brown bears in the world, officials said. Adult male bears can weigh more than 1,200 pounds by the end of the summer, while the females weigh around half that amount because they get more exercise chasing cubs around.Brown bears are omnivores, but the plentiful sockeye salmon in the Brooks River are essential to their diet.Bears need to consume enough calories before hibernation to avoid losing 15-30% of their body weight, according to the National Park Service.The fat bear frenzy began as Fat Bear Tuesday in 2014, aimed at celebrating the Alaskan bears' winter weight gain and the thriving ecosystem supporting them. Now, thousands of people from around the globe flock to FatBearWeek.org and cast their votes for the chunkiest bear that has captured their hearts.The contest draws nearly one million votes each year, according to park officials. ...read more read less