Except as otherwise provided in this section, compensation shall be payable under this chapter in respect of disability or death of an employee, but only if the disability or death results from an injury occurring upon the navigable waters of the United States (including any adjoining pier, wharf, dry dock, terminal, building way, marine railway, or other adjoining area customarily used by an employer in loading, unloading, repairing, dismantling, or building a vessel).