For me Katmai is about seeing and being with brown bears... grizzlies... Ursus arctos. In mid July, when the salmon runs are the heaveist and attract many bears, I went to Brooks Camp in Katmai to experience the place and photograph the bears. It also is a great place for fishing (while taking turns looking out for bears.)
Katmai is about a two and a half hours flight from Anchorage. First to King Salmon with a commercial flight and then a scenic twenty minute flight in small a float plane to Brooks Camp. Upon arrival at Brooks Camp your luggage is pick up and delivered a short distance to the Brooks Lodge. From there it will be taken to the cabins, if you are staying at the lodge or you can take a cart and wheel your luggage to the camping sites about a quarter of a mile down the beach on a well maintained trail. This is important information, one camper had two heavy photo suitcases full with at least 80 lb of photo gear. He had to pay extra since the load limits on the planes is 50lb. Upon arrival you are acquainted with bear safety by watching a video provided by the rangers, you are mandated to stay a way a least 50 yards from the bears although the bears do not obey this, I guess they did not see the video. Since a stay at the lodge is limited to three night and is pricey, I decided to camp for six nights at the national park camp site and purchase meals at the lodge for about fifty dollars a day for three hardy meals. There are very nice and new storage and cooking/eating facilities in the camping area, and the view from the camp ground beach is impressive. The main reason I stayed six nights is that I wanted the opportunity for good weather, Katmai is often cloudy and rainy. During the six days I was there I had the good fortune of three days of partly to mostly sunny with good light for morning and evening photos.
There are three activities in Katmai, well, there are many more but these were my focus: observing and photographing bears from the observation platforms, hiking and photographing, hanging out in the lodge, talking to other photographers and travelers and looking at fancy photo gear. Excellent wild life photographers are frequent visitors, good opportunity to learn in the filed, from experts.
The Valley of the Ten Thousand Smokes, site of the largest volcanic eruption, is a worth while destination to visit while at Brooks Camp. The park service has a shuttle to the valley where you can hike, ranger escorted or otherwise, into the valley's ash canyon, it's quite the sight.
Other then bears the place has abundant wild life, lucky visitors saw a gray wolf, lynx, moose, in the same areas where the bears are viewed. Birds of prey such as eagles, osprey and assorted other birds also abound. It's a wildlife photographer's place to be.