The Central American nation kick off their Group D campaign against Uruguay on Saturday, before coming up against Italy and England in one of the tournament's toughest pools.
However, Marin feels Costa Rica are well prepared for their curtain raiser, and is hopeful the team can perform to their potential.
"Now there is no doubt we have everything clear," he said. "Yesterday and today working with the team that will face Uruguay and I think there is no doubt, just hope that tomorrow everything goes well and we can give a good show."
Costa Rica are competing in their fourth World Cup and their third in the last four stagings, having failed to qualify for South Africa four years ago.
Their best performance at the global showpiece remains their progression to the last 16 at Italia 90.
