Ezekiel Elliott ain't letting his off the field issues keep him from having a good time -- the embattled running back partied on a Texas lake the day after the Cowboys' 2nd preseason game. 

TMZ Sports has pics of Zeke partying Sunday afternoon on Lake Lewisville in North Texas -- a notorious party spot located about 20 miles from Dallas. 

Multiple lake sources (yeah, we got those) tell us Zeke was just chillin' on a couple different boats and talking to friends. No one saw him drink any alcohol or get into any kind of negative situation. 

A rep for Elliott says Cowboys players had the day off -- so it's not like he was doing anything scandalous. 

It's almost like Zeke's sending a message that he refuses to lay low in the days leading up to his appeal hearing -- in which he'll fight the NFL's 6-game suspension from the domestic violence investigation

The hearing is set for August 29 and we're told Elliott's team is gearing up for a battle.