The attenuation of 14.1-Mev neutrons in water has been studied under conditions simulating an isotropic point source of monoenergetic neutrons in an infinite water medium. The migration area of thermal neutrons (⟨r2⟩th/6) was found to be 156 ± 6 cm2. The “age” of indium resonance neutrons was measured to be 150 ± 6 cm2. Fast neutron dose measurements are in agreement with the theoretical calculations of Goldstein et al.