At least 158 positive tests have been traced to hockey in the past two months, and Sununu's temporary ban impacts hundreds of players, from young children to aspiring pros.
The governor said it was necessary to drop the gloves and face off with the Covid-19 threat now.
"This is not a decision taken lightly by any means," Sununu told reporters Thursday. "But we have six outbreaks now (traced to hockey rinks). We've been working with this community for a couple months. It's not getting better. It's not in a crisis situation yet. But my job is to make sure that we're handling things before they become a crisis."
"I feel bad for our hockey players, and all hockey players in the state, but everyone's health and well-being is the top priority," UNH spokesman Doug Poole said in a statement Friday.
Dartmouth players had just started practicing in small pods of six to eight this week, but now Big Green skaters have exited the ice in favor of the weight room.
"At this time, the Dartmouth hockey programs are in compliance with the state’s mandate," Dartmouth spokesman Patrick Salvas said on Friday. "That means they have halted all on-ice activities and returned to strength and conditioning work until further notice."
Some coaches, parents and players believe the shutdown is a heavy-handed power play by Sununu.
Andrew Trimble, general manager of the Eastern Hockey League Premier team, the New England Wolves in Laconia, said increased protocols for face coverings could have been a less drastic move.
"Maybe if we (took) baby steps toward that, instead of a two-week shutdown, that would not be so abrupt," Trimble told NBC Boston.
The governor said he appreciated the concern but insisted the two-week shutdown is a minor penalty to pay for the greater goal of keeping Granite State residents safe.
"It's a small sacrifice, really, to make sure that we're saving the rest of the season and not ignoring what could become a much more serious situation down the road," Sununu said.
The governor's order includes all sports played on ice, so figure skaters and speed skaters will also be locked out of rinks for two weeks, a state spokesman said Friday.
New Hampshire, with 1.3 million residents, is the 41st most populous state in the union. But of all states that have produced players for the NHL, it ranks 16th, according to data from USA Hockey, the sport's domestic governing body.
Dartmouth alum Ben Lovejoy, a recently retired defenseman who did stints with the Pittsburgh Penguins, Anaheim Ducks, New Jersey Devils and Dallas Stars, played in 544 games - the most of any New Hampshire product.
In another New England state, Connecticut, Yale University raised its Covid-19 alert status to yellow from green on Thursday after 18 members of its men's hockey team tested positive for the coronavirus.
"All varsity athletic teams and intramural programs have ceased in-person training activities for at least the coming week," Stephanie S. Spangler, vice provost for health and academic integrity, said in a special alert to the Yale community.