Japanese researchers recently set a record with the deepest in-situ observation of a criniod. In the words of the authors,
Previous records of stalked crinoids from hadal depths (exceeding 6000 m) are extremely rare, and no in-situ information has been available. We show here that stalked crinoids live densely on rocky substrates at depths over 9000 m in the Izu-Ogasawara Trench off the eastern coast of Japan, evidenced by underwater photos and videos taken by a remotely operated vehicle.
Oji, T., Ogawa, Y., Hunter, A., & Kitazawa, K. (2009). Discovery of Dense Aggregations of Stalked Crinoids in Izu-Ogasawara Trench, Japan Zoological Science, 26 (6), 406-408 DOI: 10.2108/zsj.26.406
[googlemap lat="34.27083595165" lng="141.85546875" width="500px" height="500px" zoom="4" type="G_SATELLITE_MAP"]Izu-Ogasawara Trench[/googlemap]