I assume you are talking about the Delaware River (which forms the border between PA and NJ). Anyway back in the 1970s and 1980s I had a time share at Shawnee-on-the-Delaware in the Pocono Mountains in Eastern PA. My 3 sons and I would tube or sometimes raft down the Delaware River while on vacation at Shawnee. Kids would also swim in a branch of the Delaware River that ran thru the golf course at Shawnee and find 100s of golf balls. For several years I never had to buy any balls - just used the ones the kids found !!
Take care,
Jerry "Floating down memory lane" Birl