T-Mobile Park is a retractable roof stadium in Seattle, Washington, United States. It is the ballpark of Major League Baseball's Seattle Mariners and has a seating capacity of 47,929. It is in Seattle's SoDo neighborhood, near the western terminus of Interstate 90. It is owned and operated by the Washington State Major League Baseball Stadium Public Facilities D…T-Mobile Park is a retractable roof stadium in Seattle, Washington, United States. It is the ballpark of Major League Baseball's Seattle Mariners and has a seating capacity of 47,929. It is in Seattle's SoDo neighborhood, near the western terminus of Interstate 90. It is owned and operated by the Washington State Major League Baseball Stadium Public Facilities District. The first game at the stadium was played on July 15, 1999.