How to run in the heat

In the Runners' World article 'Heat Tested: A Miami club's best tips for summer running,'John Hanc gives smart advice for running in the summer heat.

I follow his first tip - run early in the morning. I also agree with the advice to run intervals inside, on a treadmill in the air conditioning.

I would love to find a way to do a 'duathlon' type workout like he proposes, running to a cool lake or swimming hole, splashing around, and then running back.

How do you keep cool in the summer?