Unlike the rest of the teams on this list, the Mariners have never reached the World Series. The closest they came was in 2001. That team won 116 games during the regular season and cruised into the ALCS.
There, they would meet the three-time defending champion Yankees. New York won the first two games of the series in Seattle. The Mariners bounced back to win Game 3 but dropped the final two games and saw their season end, despite having a stacked roster that featured John Olerud, Mike Cameron, Carlos Guillen, Edgar Martinez, Bret Boone, and a young Ichiro Suzuki.
The Mariners then did not reach the postseason again until 21 years later.
Last year, the Mariners were a Wild Card team and swept the Toronto Blue Jays in the Wild Card Series before a matchup with the Houston Astros in the ALDS.
But Houston was red-hot and pulled off a three-game sweep in the Division Series to advance to their sixth straight ALCS. The Mariners did not reach October this year and are hoping that another 21-year stretch of no playoff games doesn't start after 2023.