A genre used to describe Mastodon's 2004 concept album, Leviathan, which is based on the story of Moby Dick.

Frustrated that they were unable to fit the album into existing genres, fans of the band coined the term to point out the inherent humor in dedicating a full-length metal album to the topic of a whale. The album can be most accurately described as a mix of heavy metal, metalcore, and progressive metal.
Split your lungs with blood and thunder
When you see the white whale
Break your backs and crack your oars, men
If you wish to prevail
by unearth June 25, 2008
A "genre" of music used to describe bands with at least one album in which the cover artwork displays a whale. This is a popular tag used amongst music sites such as last.fm.

Albums that fit this description:
"Leviathan" by Mastodon
"From Mars to Sirius" by Gojira
"The Call of the Wretched Sea" by Ahab
When they couldn't find an accurate classification for Mastodon's "Leviathan", fans took hold of the cover art and thus defined it as whalecore.
by Deathgrind > you November 4, 2008
Contrary to what unearth said (Mastodon is obviously Sludge-Progressive Metal, but could be called whalecore), Whalecore is a subgenre of Heavy Metal that includes a very long, droned, slow songs with some heaviness, and a very melodic flow.
Ahab- The Hunt www.youtube.com/watch?v=fHVkJgwAXgE is a perfect example of whalecore
by YM54 February 3, 2012
Whalecore is a genre of music. Known for combining elements of mainly progressive metal with whale song.
Mastodon aren't real Whalecore, they don't have any singing whales you prick!
by The Strat Man June 24, 2008
1:An act comparable to giant prehistoric blue whales with wings that scream whilst breathing fire , dick-slapping innocent human folk with its distinctive 15 foot long dork , and dropping 20 gallon bombs of acidic sperm that rains on the cities below.

2: to throw tupperware at a vietnam war veteran to trigger PTSD
"That show was fucking whalecore! Wait , no , nothing is that bad ass"

"My grandpa wouldn't let me stay the night at my friend's house , so I gave him a dose of whalecore"
by SeanJacob April 15, 2008