The collision ripped a hole into the back of motorboat that had to be towed ashore.
The accident occurred just before 1 p.m. on Sunday, according to the Coast Guard.
A 26-year-old woman was thrown overboard into Sandy Hook Bay. She was airlifted to Jersey Shore Medical Center with a broken pelvis.
Her 28-year-old fiance, who jumped in after her, is also being treated for serious injuries.
It's not thought alcohol was a factor in the crash, officials said.
NJSB is currently investigating.
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