Some diving and snorkeling schools require snorkelers to wear an inflatable vest, similar to a personal flotation device.
They are usually bright green, yellow or orange and usually have a device that allows users to inflate or deflate the vest to adjust their buoyancy.
However these devices hinder and prevent a snorkeler from free diving to any depth.
A wet suit of appropriate thickness and coverage is suggested as they do provide some thermal protection, and extra buoyancy without as much resistance to submersion.
Snorkel Vest Tip - Experienced snorkelers often start to investigate amateur free-diving, which should begin with some training from a dive instructor or experienced free-diver.