ORLANDO, Fla. -

SeaWorld Orlando trainers on Monday began wearing new, custom-designed emergency vests as a safety improvement in the wake of Dawn Brancheau's death in 2010.

Starting with Monday's 11:30 a.m. performance of the show "One Ocean," trainers who work in close proximity of killer whales donned the vests, which become buoyant with the pull of a cord.

The emergency vest also has a small scuba tank and regulator, which provides a few minutes of air, SeaWorld trainers said.  The vests, described as lightweight, can also break-away so trainers can ditch them, if necessary. 

SeaWorld said it worked on creating the vest for more than three years, testing different prototypes in trying to find the best technology. 

The park said the vest is just one aspect of many safety improvements made after a killer whale pulled Brancheau underwater, killing her. Other safety changes include a quick-rising floor in one of the park's pools, automatic gates between the pools and distance protocols -- 18 inches away from whales while standing, 3 feet while kneeling and approaching a whale from its side on the "slideout" ledge.

When officials were asked how the vest would have impacted Brancheau's situation, SeaWorld replied, "We don't know."

SeaWorld shows will not change as a result of trainers wearing the new vests, park officials said.

The vests are not related to mandates issued by the Occupational Safety and Health Administration.