The Kemah marina was evacuated Wednesday evening after police said some sort of suspicious device was found.
After eight hours to finally clear the scene, officials said the device found was an old military device that had washed up on the marina many years ago.
People on the boardwalk itself were not in any danger and were evacuated.
A woman and her husband were walking along the marina around noon on Wednesday when they spotted the device, sitting in about a foot of water.
"My husband says 'I think that's a bomb,'" said the woman. "I looked and I said 'I think it is, too.'"
The two quickly called marina management.
"We knew that it should have been treated as dangerous any time you see something like that," said the woman. "You need to treat like that so we went right up and reported it to the office."
A team of police arrived at the scene and called for backup as FBI and Coast Guard officials joined forces.
"It was finally determined that it was a military training device," said Bill Kerber of Kemah Emergency Management. "It's got a big hole in the side of it. It's not an active device."
Kerber said the device could possibly have come from a old marine salvage that used to be in the area.