McIntyre, P.M. Assadi, S. Bannert, S.P. Breitschopf, J. Chavez, D. Gerity, J. Kellams, J.N. Pogue, N. Sattarov, A. JACoW Geneva, Switzerland 978-3-95450-180-9 10.18429/JACoW-NAPAC2016-MOB2CO03 English 13-16 MOB2CO03 ion collider luminosity hadron dipole Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-NAPAC2016-MOB2CO03 https://jacow.org/napac2016/papers/mob2co03.pdf A design is presented for a hadron collider in which the magnetic storage ring is configured as a circular pipeline, supported in neutral buoyancy in the sea at a depth of ~100 m. Each collider detector is housed in a bathysphere the size of the CMS hall at LHC, also neutral-buoyant. Each half-cell of the collider lattice is ~300 m long, housed in a single pipe that contains one dipole, one quadrupole, a correction package, and all umbilical connections. A choice of ~4 T dipole field, 2000 km circumference provides a collision energy of 700 TeV. Beam dynamics is dominated by synchrotron radiation damping, which sustains luminosity for >10 hours. Issues of radiation shielding and abort can be accommodated inexpensively. There are at least ten sites world-wide where the collider could be located, all near major urban centers. The paper summarizes several key issues; how to connect and disconnect half-cell segments of the pipeline at-depth using remote submersibles; how to maintain the lattice in the required alignment; provisions for the injector sequence.