Shirtless Liev Schreiber and Son Samuel at an NYC Water Park

A shirtless Liev Schreiber took playful aim at his son Samuel, pointing a water gun at him while they cooled off at an NYC park today. The father and son splashed around in their swim trunks and ran through the sprinklers together as they enjoyed the warm temperatures on the East Coast. Naomi Watts and their older son, Sasha, weren't along for the outing, but the whole Watts-Schreiber family has been enjoying the summery weather lately. The foursome took off for a Barbados vacation in April and stopped for ice cream close to their Big Apple home earlier this month. Both parents have been taking a brief break from work but are set to costar together in the boxing film The Bleeder, which is based on a true story. Naomi is also said to be in talks to act opposite Jesse Eisenberg in director Noah Baumbach's upcoming movie While We're Young.