Tecomán is a working agricultural city near the Colima coast, best known in Mexico as a lime capital rather than as a polished beach town. That is part of the point: the city is practical, hot, and sometimes rough-edged, while the interesting travel happens along the beaches, lagoons, and seafood palapas south and west of town.
The strongest reason to come is Boca de Pascuales, a serious surf beach with heavy Pacific waves and a simple village feel. Playa El Real and Playa Tecuanillo give you other versions of the same coast, with dark sand, open water, birds, and enramadas serving fish and shrimp.
Tecomán is not a destination for aimless strolling after dark; pay attention to local safety advice and use taxis when needed. But if you are already in Colima or Manzanillo and want a day of surf, coconuts, lagoons, and a less packaged Pacific coast, it has a clear identity.