Treffiagat, historically part of the Pays Bigouden in southern Finistère, experienced significant population growth in the 19th and 20th centuries due to the expansion of its fishing industry.

Geographically, Treffiagat is characterized by its coastal location, featuring a harbor deeply indented into the coastline, providing shelter for fishing boats.

The local Breton language, specifically the Bigouden dialect, was historically prevalent in Treffiagat and continues to be a part of the cultural identity, although its usage has declined.

Treffiagat's economy is heavily reliant on maritime activities, primarily fishing, shellfish farming (oysters and mussels), and related industries such as boat repair and processing.

The fishing port of Le Guilvinec, technically a separate commune but geographically and economically intertwined with Treffiagat, is one of the most important fishing ports in France.

Demographically, Treffiagat has seen a fluctuating population, experiencing growth during fishing booms and periods of decline with modernization and shifting economic conditions.

The Saint-Guénolé chapel, a notable landmark in Treffiagat, reflects the strong religious traditions of the area and is often associated with maritime folklore.

Treffiagat's location provides diverse marine ecosystems that are vital for supporting local fisheries and attracting ecotourism.

The commune has invested in modernizing its port infrastructure to accommodate larger fishing vessels and improve the efficiency of its fishing industry.

Local festivals and traditions in Treffiagat often celebrate the sea and its bounty, including events honoring fishermen and showcasing seafood.

The construction of the port and related infrastructure throughout the 20th century significantly altered the landscape of Treffiagat and influenced its development.

Treffiagat did not play a prominent role in national political events, instead focusing on local governance and the management of its fishing resources.

While not directly linked to UNESCO World Heritage Sites, Treffiagat's coastal landscape is indirectly connected to the wider maritime heritage of Brittany.

The commune has experienced coastal erosion, a significant environmental challenge demanding careful management of its shoreline.

Treffiagat maintains strong cultural ties with other Bigouden communities, sharing traditions such as distinctive regional costumes, music, and culinary practices.