Lots to see and do that should interest the boys. Neat little waterfall at your 4th portage to play around in. The island sites before the North/South split are nice, the site o the North K adjacent to the Conchu Lake portage (not the one on Conchu) is really nice, believe it's 1143. If you head down the South K, there are three sites close to each other (1129, 30, and 31?) that are all nice. 1131 you can fish the rapids from camp. Nice waterfall about 2/3rds of the way down the long 220 rod portage on the North K, look for side trails you can't see it from the portage. The island site on Clear Lake would be good too.
Did this trip with a group of similar boys. Pushed it down to Gabbro for first 2 days. Look at sites 1714 or 1710 along north side. Nice camps for boys, quiet fishing in back bays.
Then we backtracked to where the Kawishiwi splits....NE corner of triangle. Sites 1148 or 1141 should make them happy. Good fishing along the river, boys caught bluegills from camp, some rock jumping. Stayed there 2 more nights and had a shorter, upstream out-day.
First off, congrats on taking your boys on a canoe trip into the wilderness. A trip well done can very likely turn your young sons into lifelong paddling partners. I sure hope so. I took my son on his first trip when he was eight and he's still paddling with Dad to this day - and he turns 31 at the end of March.
Regarding your post, you may have used the term generically, but I hope you meant cliff JUMPING, and not cliff diving. Please don't take unnecessary risks diving into unknown waters, especially hours from help. It's safer and just as much fun to jump.
Plan great meals and don't move every day. Your boys have plenty of time to get older and do longer trips. They'll be just as happy two or three lakes in and basecamping for a few days. Just my two cents from past experience.
Good luck in your planning. Exciting!
A buddy that I do a guys trip in June are planning a trip into Lake One, but heading west down the Kawishiwi River with our nine and eight year old boys in July.
Does anyone have recommendations as to where to go for an enjoyable four day trip with some energetic boys who just want to swim and fish all day? A campsite close to cliff diving is a must. Any recommendations are welcome.