A dead gray whale was found off the northwest side of Vashon Island, according to the National Oceanic and Atmospheric Administration.
The whale was spotted by a boater early Tuesday in the area of north Colvos Passage.
Cascadia Research is responding on behalf of NOAA and will tow the whale to shore to be examined.
A necropsy to determine its cause of death will be performed Wednesday or Thursday.
This is the same gray whale that was spotted April 6 in the Ballard Locks. NOAA said it was under-nourished.
NOAA says that this is the time of year when whales typically migrate to the Arctic. Though it is not uncommon for whales to show up in the Puget Sound, they do not usually stick around in high-traffic areas such as the Locks.
The whale wasn't strong enough to make the migration to the Arctic and wandered into Puget Sound looking for food or a place to die, NOAA officials said.
Cascadia Research says there are a number of gray whales in the area.