Explore the beauty of the Chesapeake Bay's rivers, and learn firsthand about the threats to their vitality, by spending some time on - or in - them.

The Sojourn on the Patuxent, a leisurely five-day canoe/kayak trek covering 20 miles of the river, pushes off on Thursday, June 18, from around Upper Marlboro. It features a blues and folk concert, talks by local experts, an owl prowl, moonlight creek paddle, camping and camaraderie. You can join for as short or long a time as you like, but space is strictly limited. For registration or other information, go here or call Patuxent Riverkeeper at 301-249-8200 ext 2.

If that's not enough, or too soon, then there's the Potomac River Ramble from June 24 to 28, another paddling expedition that features riverside camping, catered meals, live music, restoration projects and environmental education. Sponsored by the Interstate Commission on the Potomac River Basin and River and Trail Outfitters, this year's ramble takes in both the "nation's river" and one of its tributaries, the Monocacy, starting at Pine Cliff Park in Frederick. Learn from experts about the river's ecology and its problems, including aquatic species and inter-sex fish. No paddling experience required. For more information go here.

(Photo courtesy of the Interstate Commission on the Potomac River Basin)