christopher swain donned protective suit to swim through gowanus canal .
brooklyn waterway is famous dumping site for toxic industrial waste .
roughly 377million gallons of diluted raw sewage poured in each year .
swain quit two-thirds of a mile into 1.8-mile journey and said it was like ` swimming into a dirty diaper '
swimmer gargled peroxide and had special tablet on hand to fight against contaminated water entering his body and making him sick .
he urged faster cleanup of the canal , which is slated for dredging in 2017 .