JAMSTEC, the Japan Agency for Marine-Earth Science and Tecnology is the Japanese national research institute for marine-earch science and technology.
In April and May 2018, JAMSTEC and the Japanese Splatoon Twitter account announced a collaboration and cross-promotion called Jamsteeec, which included:
- The Splatfest Unknown Creature vs Advanced Technology
- The Inkling world's version of JAMSTEC, with a few details:
- The Oceanic Hard Hat, designed after the real-world JAMSTEC hard-hats.
- The research and deep-earth drilling ship, CHIKYU, was added to the background of the Manta Maria stage.
- The deep-sea submarine Shinkai 6500 was shown to exist in the background of a level in the Octo Expansion.
- Videos showing real-life deep sea squids and Octopuses, in comparison with Inklings and Octolings.
- Several posts on the real-life creatures that inspired some of the characters in the Octo Expansion, including C.Q. Cumber (sea pig) and Iso Padre (giant isopod).
- An free "open day" held on 12 May 2018, at the JAMSTEC headquarters in Yokosuka was promoted on the SplatoonJP Twitter 
- Splatoon 2 collaboration activities at the event itself, such as presentation of the "research reports", an exhibition stamp rally, photo ops, and coloring book illustrations.
The JAMSTEC logo, as it appears in Splatoon 2.
A promotional image for the Oceanic Hard Hat.
Unknown Creature vs Advanced Technology Splatfest shirts.
Promotional image for the Shinkai 6500, as it appears in the Octo Expansion.
A promotional image for the ship, CHIKYU, appearing in the background of the Manta Maria stage.
The CHIKYU in the distance, behind an Inkling boy.
A view of the CHIKYU at night, from the Manta Maria.
Unknown Creature va. Advanced Technology Splatfest.
Hisashi Nogami, dressed as the "Squid Research Labs" representative, posing in front of the research vessel Yokosuka at JAMSTEC HQ
- JAMSTEC on Wikipedia
- Jamsteeec official site
- JAMSTEC public relations Twitter account
- Article on the collaboration on the Nintendo Europe news site