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)

See also

NUTS of Turkey

External links TURKSTAT

Sources ESPON Database