Smith signed an extension with the Padres last summer and had apparently been told that he would get some say over whether or not he would be traded.
The 32-year-old is coming off a solid 2014 season after he hit .266/.367/.440 with 12 home runs and 48 RBI but became expendable following a slue of outfielders acquired by the Padres this winter.
Smith now heads to Seattle where he will share time in right field with Justin Ruggiano.
The Padres return in this deal is Maurer who would appear set for a bullpen spot but could also start.
Maurer, 24, has appeared in 60 games over the last two seasons including 21 starts. He owns a 5.60 ERA and a 1.47 WHIP.