Leviathans of Jupiter

Grant Archer, now director of Jupiter Station, cannot let go of an obsession from twenty years earlier: the city-sized lifeforms he glimpsed while diving into Jupiter's crushing seas. When new evidence suggests those leviathans may be more than animals, Archer has to weigh scientific wonder against the political and personal costs of forcing another descent. Part of Ben Bova's Grand Tour series, where the solar system's oceans hide intelligence humanity isn't ready for.