According to the U.S. Census Bureau, the county has a total area of 4,119 km² (1,590 mi²). 2,496 km² (964 mi²) of it is land and 1,622 km² (626 mi²) of it is water. The total area is 39.39% water.
There are 16,871 households out of which 32.70% have children under the age of 18 living with them, 59.80% are married couples living together, 8.60% have a female householder with no husband present, and 27.90% are non-families. 24.30% of all households are made up of individuals and 11.60% have someone living alone who is 65 years of age or older. The average household size is 2.60 and the average family size is 3.08.
In the county the population is spread out with 26.90% under the age of 18, 7.60% from 18 to 24, 27.00% from 25 to 44, 23.00% from 45 to 64, and 15.40% who are 65 years of age or older. The median age is 38 years. For every 100 females there are 98.50 males. For every 100 females age 18 and over, there are 94.80 males.
The median income for a household in the county is $36,870, and the median income for a family is $42,306. Males have a median income of $32,101 versus $21,376 for females. The per capita income for the county is $17,089. 10.40% of the population and 7.60% of families are below the poverty line. Out of the total people living in poverty, 13.10% are under the age of 18 and 9.30% are 65 or older.
