A golf ball has a relatively light core center. The golf ball may have a thermoplastic core center with diameter about 28-35 mm and flexural modulus under about 15,000 psi; a thermoplastic core layer with flexural modulus ≦about 15,000 psi and >the core center's flexural modulus; and a cover ≧about 2 mm thick with specific gravity ≧about 2 g/cm3 and flexural modulus ≧about 15,000 psi. Alternatively, the core center has diameter about 21-29 mm, flexural modulus the core center flexural modulus; and the cover is ≧about 1 mm thick, has specific gravity ≧about 1.1 g/cm3, and flexural modulus ≧about 15,000 psi.