From the Wikipedia page 
Pwani Region is one of Tanzania's 31 administrative regions. The regional capital is the town of Kibaha. According to the 2012 national census, the region had a population of 1,098,668, which was slightly lower than the pre-census projection of 1,110,917.:page 2 From 2002 to 2012, the region's 2.2 percent average annual population growth rate was the seventeenth-highest in the country. It was also the 21st most densely populated region with 34 people per square kilometer. 6 With a size of 32,407 square kilometres (12,512 sq mi), the region is slightly larger than the U.S. state of Maryland (32,133 square kilometres (12,407 sq mi)).
The region is bordered to the north by the Tanga Region, to the east by the Dar es Salaam Region and the Indian Ocean, to the south by the Lindi Region, and to the west by the Morogoro Region. The word "pwani" in Kiswahili means "coast".