The Seattle Mariners are playing today, Sunday, May 18, 2025, but the exact opponent and location are not explicitly listed in the current search results. The available schedules show upcoming games but do not specify a game on May 18. The Mariners' schedule around this date includes games against teams like the Los Angeles Angels, Texas Rangers, and others, but no direct entry for May 18 is visible in the provided data

. For the most accurate and up-to-date information on where the Mariners are playing today, checking the official MLB Mariners schedule or a live sports update source would be recommended.