  We generalize Conway's approach to integral binary quadratic forms on Q to
study integral binary hermitian forms on quadratic imaginary extensions of Q.
In Conway's case, an indefinite form that doesn't represent 0 determines a line
("river") in the spine T associated with SL(2,Z) in the hyperbolic plane. In
our generalization, such a form determines a plane ("ocean") in Mendoza's spine
associated with the corresponding Bianchi group SL(2,A) in hyperbolic 3-space.
