Bob Selfridge is no stranger to cold sea water, but this year his immersion in January has an educational edge to it.

“Originally, I would just do a polar plunge on New Year’s Day – wash away the old year,” said Selfridge, an emergency medical technician who at age 58 is in his 42nd year of ocean lifeguarding on the beach patrol. In Barnegat Light, where he lives, he is also lieutenant and training officer of the Barnegat Light Volunteer Fire Co. and captain of the Barnegat Light EMS.