) front Oregon's Pacific Ocean coastline, where the land then rises into the Coastal Mountain Range and the Klamath Mountains of the south; both a series of relatively low, heavily-forested peaks, punctuated by numerous small lakes.
Directly to the east of those mountains, the Willamette Lowlands stretch south from the Portland area about 175 miles. This fertile strip of land is dissected by the Willamette River which rises in the Cascades, to then flow north into the Columbia River.
East of the lowlands stand the majestic Cascades. This range of (volcanic in origin) peaks includes Mt. Hood, Oregon's highest point, as well as many other major mountains including Mt. Jefferson, Mt. McLoughlin and the Three Sisters. These forested mountains contain many lakes, including Crater Lake (America's deepest lake) at 1,932 feet deep.
The Columbia Plateau extends south from Washington to cover much of eastern Oregon. Formed by ancient lava flows, it's a landscape of deep, wide valleys and rugged mountains, including the Blue and Wallowa. Hell's Canyon, dissected by the Snake River on Oregon's border with Idaho, is the deepest gorge in America, with a maximum depth of 7,900 ft.
The Harney Basin, a part of the larger Great Basin region of the western United States, is an arid and flat stretch of land that has no natural outlet to the sea. Harney Lake, Malheur Lake and the Steens Mountains are its major features.
Oregon's most significant rivers are the Columbia and Snake. The Columbia rises in British Columbia, Canada, then flows south through Washington to Oregon, forming most of the natural northern border between the two states. The Snake rises in the Grand Tetons of Wyoming and flows all the way to the Columbia River in Washington State.
Other rivers of note include the Deschutes, John Day, Owyhee, Rogue and Willamette.
For a detailed look at the topography of Oregon, view this topography map.