Meson sites
Hi I don't know about how well imaging from landsat works for the bottom of the ocean, but I will wager that at TL15 any vehicle no matter how heavily armored will melt in contact with magma. You need some form of ultra refrigeration to keep your hull from slagging perhaps you could use the meson gun as a heat dump, but you have to do some considerable cooling to keep such a sight habitable. At TL15 I don't see it happening. Maybe as an ancient artifact but not TL15. Good night 1AM Scotty