According to the U.S. Census Bureau, the county has a total area of 1,919 km² (741 mi²). 1,163 km² (449 mi²) of it is land and 756 km² (292 mi²) of it is water. The total area is 39.40% water.
As of the census2 of 2000, there are 707,161 people, 254,103 households, and 171,265 families residing in the county. The population density is 608/km² (1,575/mi²). There are 260,576 housing units at an average density of 224/km² (580/mi²). The racial makeup of the county is 59.49% White, 3.51% Black or African American, 0.44% Native American, 20.04% Asian, 1.33% Pacific Islander, 10.17% from other races, and 5.02% from two or more races. 21.88% of the population are Hispanic or Latino of any race.
There are 254,103 households out of which 31.10% have children under the age of 18 living with them, 53.00% are married couples living together, 10.10% have a female householder with no husband present, and 32.60% are non-families. 24.60% of all households are made up of individuals and 8.40% have someone living alone who is 65 years of age or older. The average household size is 2.74 and the average family size is 3.29.
In the county the population is spread out with 22.90% under the age of 18, 7.90% from 18 to 24, 33.20% from 25 to 44, 23.50% from 45 to 64, and 12.50% who are 65 years of age or older. The median age is 37 years. For every 100 females there are 97.80 males. For every 100 females age 18 and over, there are 95.60 males.
The median income for a household in the county is $70,819, and the median income for a family is $80,737. Males have a median income of $51,342 versus $40,383 for females. The per capita income for the county is $36,045. 5.80% of the population and 3.50% of families are below the poverty line. Out of the total people living in poverty, 6.00% are under the age of 18 and 5.10% are 65 or older.
Cities and towns