noun - Three-wide (3-wide or 3 wide) is a formation of three open water swimmers or triathletes swimming side-by-side during a race or training session.
There was a three-wide coming around the last turn buoy.
Its equivalents (4-wide, 5-wide, 6-wide, etc.) are used when there are more individuals swimming side-by-side.
Usage dating to circa 2001 from Steven Munatones in Huntington Beach, California as adopted from the modern-day application of a NASCAR term.
with Darren Miller
, Jamie Patrick
, Jen Schumacher
and Oliver Wilkinson
across the Strait of Gibraltar