We swim alongside the iron-masted barge on the leeward edge, protected from the current. Next to us the wooden planking appears like a lizard’s skin—horny where it has worn back from the knots, and clustered with zebra mussels. Mike appears to be levitating ahead of me, his hands calmly crossed beneath his chest, parallel to the river bottom. From somewhere unidentifiable the thrum of a passing tanker echoes around us.