Kocaeli Subregion
# Kocaeli Subregion

The Kocaeli Subregion (Turkish: Kocaeli Alt Bölgesi) (TR42) is a statistical subregion in Turkey.

## Provinces

* Kocaeli Province (TR421)
* Sakarya Province (TR422)
* Düzce Province (TR423)
* Bolu Province (TR424)
* Yalova Province (TR425)
