(CNN) -- An underwater explorer believes he has found the Santa Maria -- the famous flagship from Christopher Columbus' first voyage across the Atlantic.
The ship sank more than 500 years ago, so it's not easy to spot with an untrained eye. Brandon Clifford told CNN he first found the shipwreck more than a decade ago on a shallow reef near Haiti's northern coast.
- Read More from CNN: Shipwreck found off Haiti coast may be Santa Maria
Clifford says he's now confident the ship is the Santa Maria, which ran aground off the coast of Haiti in December 1492.
The underwater explorer says a cannon found at the site features a 15th-century design. He considers that cannon to be the "smoking gun", part of the proof the ship is the Santa Maria.
Clifford and his team actually first found the wreck in 2003, but he says archaeologists originally "misdiagnosed" the age of the cannon.
He and a team of experts returned to the site a few weeks ago.