Sentinel Gap

Sentinel Gap is a water gap in the Saddle Mountains where the Columbia River cuts through the mountain range. The passage reveals massive basalt cliffs that form the walls on both sides of the river as it flows eastward.

Massive glacial floods during the Ice Age carved this gap into the Saddle Mountains over thousands of years. These catastrophic water flows created the dramatic passage we see today.

Local tribes historically recognized this passage as a key route through otherwise impassable terrain, moving people and goods between eastern and western territories. The waterway itself held spiritual significance as a powerful natural force shaping the landscape.

State Route 243 runs through the gap with several pullouts where you can stop and view the cliffs and river. Spring and fall offer the most comfortable weather for spending time at the viewpoints.

The basalt cliffs display horizontal striations marking ancient water levels from catastrophic floods that rose several hundred feet high. These marks show how powerful the ancient waters were when they carved through solid rock.