We study the coherent dynamics of localized excitons in 100 periods of 2.5-nm-thick (In,Ga)N/GaN quantum wells with 7.5% indium concentration, measured with spectroscopic resolution through two-pulse and three-pulse photon echoes at the temperature of 1.5 K. A long-lived coherent exciton dynamics is observed in the (In,Ga)N quantum wells: When the laser photon energy is tuned across the 43-meV-wide inhomogeneously broadened resonance line, the coherence time T2 varies between 45 and 255 ps, increasing with stronger exciton localization. The corresponding narrow homogeneous linewidths ranging from 5.2 to 29μeV as well as the relatively weak exciton-phonon interaction (0.7μeV/K) confirm a strong, quantum-dot-like exciton localization in a static disordered potential inside the (In,Ga)N quantum well layers.