Tentacular Circus, like many Turquoise October songs, is an electronic song, featuring many chiptune influences and unorthodox production. It appears to contain various unusual samples of vocals, whistles, bells and trumpets. It is heard in the Octo Valley missions Gusher Gauntlet, Inkrail Skyscape, Tumbling Splatforms, Pinwheel Power Plant, and can also be heard in Squid Beatz.
Tentacular Circus (Splatoon Single Player Trailer)
Tentacular Circus was first heard in the reveal trailer for Splatoon's Hero Mode. It starts playing about 37 seconds in, after a short Cephaloparade remix. Unlike other versions, it has a proper ending, consisting of a modified version of the beginning.
Tentacular Circus is based on a portmanteau of 'tentacle' and 'spectacular'.