The three lowest diabatic potential energy surfaces for the Cl(P-2)+H-2((1)Sigma(g)(+)) van der Waals complex are derived from accurate ab initio calculations of the T-shaped (C-2v) and collinear geometries (C-infinityv), at the coupled-cluster with the single, double, and noniterative triple excitations level of theory with a large basis set. The nonadiabatic coupling (off-diagonal derivative) matrix element and the fourth, off-diagonal, diabatic surfaces are determined by separate multireference configuration interaction calculations. For the intermediate geometries the angular dependence is modeled by a simple Legendre-polynomial interpolation. Three adiabatic potential energy surfaces (PESs) are also obtained by diagonalizing the total Hamiltonian in the diabatic basis. Both the nonrelativistic and relativistic (including spin-orbit coupling) PESs are evaluated. The nonrelativistic ground state PES agrees well with the entrance channel of the Bian-Werner (BW2) PES [W. Bian and H.-J. Werner, J. Chem. Phys. 112, 220 (2000)]. The dependence on the H-2 stretching coordinate is also incorporated.