Some of my earliest childhood memories are of swimming in the Atlantic Ocean. As a kid, I loved to wade, snorkel, bodyboard and run in the waves. Now, I swim the entire length of dirty waterways like the Hudson, the Charles,and the Columbia Rivers, in order to put the problems facing our water planet squarely in the public eye.

In the process, I have survived collisions with boats, 12-foot waves, lightning storms, class IV+ rapids, giant storage dams, industrial chemicals, nuclear waste, oil slicks, raw sewage, toxic blue-green algae, and repeated Sea Lamprey Eel attacks.

Stories about my environmental adventures reached a worldwide media audience of more than two billion people, but the bulletins I sent back from the big wet world weren't always uplifting: high levels of CO2 were acidifying the oceans, manmade toxics were spewing into rivers, and fisheries were collapsing as factory ships scoured the seas.

When I was a boy, this was business as usual, but now there is a worldwide scientific consensus that we need to change our ways before our planet becomes a place where we can no longer live.

My 1,500 mile swim from Canada to Washington, D.C., isn't just designed to raise awareness of the challenges facing the ocean, but to sample the water at over 5,000 locations along my route to measure and map the effects of pollution and Climate Change, and to challenge over 50,000 schoolchildren to launch projects designed to improve the health of our ocean planet.

As usual, it is not easy. I have to deal with frigid water temperatures, nasty currents, severe storms, and dangerous fish. But if I want my daughters to inherit a healthy world, this is the least I can do.

When the effort ends, I hope it will have benefitted more than just my children. I hope there will be tens of thousands of kids leaning on their parents, teachers and caregivers to protect our ocean planet.