This address will get you onto Goat Island, in Niagara Falls State Park.

Once in the park, head towards the main parking lot, park, and then follow the signs for Luna Island.  It's only about a 5 minute walk from the parking lot.

Please Note: If you google-map Luna Island, Google thinks it's in Canada.  It's not.  It's in the U.S. and is accessed from the U.S. side of the border.  Please don't be confused.