Tampa was the last team Seattle needed to beat in order to achieve this, and they did so with Yanni Gourde scoring a goal in the process, the player they selected from Tampa Bay in the expansion draft.
Since Seattle has come into the NHL, Tampa has been a very good team, with the Lightning being the reigning Stanley Cup champions going into Seattle's first season.
Now, in their third season, Seattle knocks the final team off their list of who they were yet to beat in the NHL.