According to the U.S. Census Bureau, the county has a total area of 1,812 km² (700 mi²). 1,181 km² (456 mi²) of it is land and 631 km² (244 mi²) of it is water. The total area is 34.84% water.
As of the census2 of 2000, there are 33,616 people, 14,158 households, and 9,542 families residing in the county. The population density is 28/km² (74/mi²). There are 20,849 housing units at an average density of 18/km² (46/mi²). The racial makeup of the county is 98.46% White, 0.17% Black or African American, 0.26% Native American, 0.37% Asian, 0.02% Pacific Islander, 0.10% from other races, and 0.61% from two or more races. 0.46% of the population are Hispanic or Latino of any race.
There are 14,158 households out of which 28.20% have children under the age of 18 living with them, 56.10% are married couples living together, 7.70% have a female householder with no husband present, and 32.60% are non-families. 26.70% of all households are made up of individuals and 12.10% have someone living alone who is 65 years of age or older. The average household size is 2.35 and the average family size is 2.82.
In the county the population is spread out with 22.70% under the age of 18, 5.50% from 18 to 24, 25.60% from 25 to 44, 28.10% from 45 to 64, and 18.20% who are 65 years of age or older. The median age is 43 years. For every 100 females there are 95.10 males. For every 100 females age 18 and over, there are 92.00 males.
The median income for a household in the county is $38,686, and the median income for a family is $45,427. Males have a median income of $31,209 versus $23,161 for females. The per capita income for the county is $20,760. 10.10% of the population and 6.60% of families are below the poverty line. Out of the total people living in poverty, 12.80% are under the age of 18 and 9.50% are 65 or older.