There are three main types of vegetation in Katmai National Park and Preserve. There are coastal forests, taiga, and tundra. The coastal forests mainly have Sitka spruce and western hemlock. The taiga has a larger range of trees. There is the poplar, alder, willow, birch, and the white spruce. At the forest floor there is a large amount of moss and lichen. There are two types of tundra in this park. One is the alpine tundra, which is above the treeline, and has birch, willow, alpine blueberry, crowberry, and Labrador Tea. The other type is the permafrost area where the water can't drain properly. These areas are made up of cotton grass, lowbrush cranberry, and Labrador Tea. In the Valley of the 10,000 Smokes there is little vegetation. This is because the wind blows ash over any plants trying to grow. The few plants that do grow are grasses, sedges, willow, and some wildflowers.

The park is a great place for animals to live because there is plenty of food and water. One of the most watched animals in the park is the brown bear. It attracts many tourists to the park. The bears can reach eight to nine feet in length and weigh as much as 1500 pounds. The bear population is the greatest population of unhunted brown bears in the world.

Some of the other animals in the park are a large number of caribou. Katmai Park has the largest number of unhunted caribou in Alaska. There is also a large number of moose. The moose share there habitat with the river otters, lynx, porcupines, red foxes, snowshoe hares, and wolves. At the coast there is a large number of seals, otters, sea lions, and birds.