The team of senior Luke Smith and juniors Jesse Elkins, Walter Chiarella and Jay Guffey won both the 200 freestyle relay (1:31.30) and 400 freestyle relay (3:23.36), edging Crawfordsville in each race.
Tiger Shark freshman diver Matthew Sims finished fourth with 307.25 points. He advances to the Plainfield diving regional at 6 p.m. Tuesday.
South Putnam finished tied for sixth in the meet, while North Putnam was 10th.
Greencastle's relays will compete at the IHSAA State Finals preliminaries, slated to begin at 6 p.m. Friday at the IUPUI Natatorium.