To understand physical structures in the Korean waters, we investigated the spatio-temporal distribution of Pontella species known as indicator species of water mass using a David-Hempel neuston net from April 2002 to March 2003. Five Pontella species (P. chierchiae Giesbrecht, P. fera Dana, P. latifurca Chen and Zhang, P. securifer Brady and P. sinica Chen and Zhang) were found. Their abundance increased from May to October with increasing the surface water temperature. Pontella chierchiae predominantly appeared in the whole areas while P. latifurca scarcely occurred in coastal waters. The other three species (P. fera, P. securifer and P. sinica) were rarely found in the South Sea of Korea on August to September. We suggest that P. securifer and P. fera as oceanic species can play a role in an indicator species of the Tsushima Warm Current while P. sinica as Chinese coastal species is affected by the diluted waters of the Yantze River. We also provide re-description of the three sp