The NYPD says sun glare may be to blame for a ferry plowing into a group of kayakers on the Hudson River, an incident that is putting a focus on safety in the increasingly congested waterway. NY1's Michael Scotto filed the following report.

Kayakers in the Hudson River say the experience is often a relaxing one.

"It's such a change of pace from being in New York City," said Kaitlin Petersen of the Manhattan Community Boathouse.

But on Tuesday, that experience almost turned tragic when five people were hurt after a New York Waterway ferry crashed into their kayaks near West 39th Street. One of the injured suffered a partially severed arm.

Police say the sun may have made it difficult for the ferry operator to see the kayakers.

"Apparently, sun glare was a factor. The sun sets west, and he was looking behind him and the sun kind of blocked his vision," said Carlos Gomez of NYPD Patrol Services.  

The Hudson River Park Trust says it is aware of no similar incidents in a river that is increasingly being used for leisure.

As the river's been cleaned up and the waterfront made more accessible, more and more people have been coming out to kayak. There are now five locations along the West Side where New Yorkers can get sail boats, paddle boards or kayaks to use in the Hudson.

These small human-powered vessels are dwarfed by ferries and other commercial boats, which make about a half million trips a year in the harbor. That number is on the rise since the Great Recession took a toll on harbor traffic.

"I think five years ago, you could go out on a kayak trip and see almost no one at all some days, and that is now rarely the case," Petersen said.

The Coast Guard says kayakers and other recreational boaters have a right to travel almost anywhere in the Hudson. They just need to be on the lookout for larger, power-operated vessels, which generally are supposed to stay out of their way.

The Manhattan Community Boathouse offers free kayak lessons and trips inside an embayment. The group hopes that Tuesday's incident doesn't change perceptions of the Hudson.

"The river is just as safe as it is today as it was this past weekend," Petersen said.

The Coast Guard says it could take months before its investigation determines why the river became unsafe for a few moments on Tuesday.