Columbia River Kayaking, based out of Skamokawa, Washington (1391 WA State Rd. 4, Skamokawa, 360/849-4016, www.columbiariverkayaking.com [1]) offers guided day and multiday kayak trips along the lower Columbia River. One popular half-day excursion explores Young’s Bay and the area around Lewis and Clark’s 1806 lodgings at Fort Clatsop [2] ($75 per person).
Links:
[1] http://www.columbiariverkayaking.com
[2] http://www.moon.com/destinations/oregon/north-coast/astoria/sights/fort-clatsop-national-memorial