'It's pretty cool to find them because you never know how far they came, where they came from, who they came from. Each one tells someone's story.'
'Some of them had been found 3 or 4 times and then passed on.'
He says he's found bottles containing lottery tickets, one with a picture of Bill Clinton inside, a 'voodoo' bottle with a spooky message and notes to lost loved ones.
Pregracke started his nonprofit organization, Living Lands & Waters, back in 1998. Since then, the organization's volunteers have removed more than 7 million pounds of garbage from waterways in the U.S.
The nonprofit's website says volunteers spend nine months out of the year hosting 'river cleanups, watershed conservation initiatives, workshops, tree plantings and other key conservation efforts.'
Pregracke was also named CNN's Hero of Year in 2013 and told the outlet he found his first message in a bottle in 1997. Now, he keeps his eyes peeled for them.
'I'm always scanning, looking in every bottle for a piece of paper. You get psyched out a lot because people have stuffed napkins or wrappers in there. You get kind of excited and then, 'Oh no.''
So has Pregracke ever reunited anyone through these found messages? He says a few of the messages have included the phone numbers of the people who wrote them. He's called them, but says some of the people forgot they'd even sent a message in a bottle.