The crash occurred last week in the popular resort area and the two have been missing since, local fire chief and head of civil protection Carlos Gomez told AFP.
The small plane, a Cessna 180, which is often used used for skydiving, came down on May 7 one kilometer (0.62 miles) from the coast of Las Glorias beach in Jalisco.
Wreckage from the aircraft was found about 1,000 meters (3,281 feet) below sea level, Gomez said.
"It is still unknown whether the bodies of missing people are inside the fuselage," Gomez added.
The area has been battered by strong waves in recent days as a result of ocean swells.