What is the biggest lake in Wisconsin?

Lake Winnebago, at 132,000 acres (not counting the Great Lakes).

What is the second biggest lake in Wisconsin?

Petenwell Lake, at 23,200 acres.

Biggest inland lakes in Wisconsin: the top 10 by size

How big are the biggest lakes in Wisconsin? Here are the top 10 (not counting the Great Lakes), with their size and what to do on each.

The list

Sizes are the published surface area where one exists; the others are our own measure of the water's outline and read "about". Reservoirs shrink and grow with their level, so a dry year shows less water.

#	Lake	Size	Shoreline
1	Lake Winnebago	132,000 acres
2	Petenwell Lake	23,200 acres	about 54 mi
3	Castle Rock Lake	16,600 acres	about 63 mi
4	Chippewa Flowage	14,600 acres	about 126 mi
5	Turtle Flambeau Flowage	12,900 acres	about 135 mi
6	Lake Koshkonong	10,500 acres	about 24 mi
7	Lake Mendota	9,740 acres	about 29 mi
8	Green Lake	7,350 acres	about 30 mi
9	Lake Wisconsin	7,200 acres	about 55 mi
10	Beaver Dam Lake	6,720 acres	about 36 mi

1. Lake Winnebago

At some 132,000 acres, Lake Winnebago is a huge piece of water. Walleye, yellow perch, catfish and white bass are the draw. At about 21 ft at its deepest, it warms quickly in spring. Its bed shows two point drop-offs and an upper arm worth a first look.

Lake Winnebago today: water temperature, bite times and the 3-D lake bed

2. Petenwell Lake

At some 23,200 acres, Petenwell Lake is a big lake. You will find it near Rome. It is the Wisconsin River behind Petenwell Dam. It holds walleye, northern pike, largemouth bass and smallmouth bass. At about 42 ft at its deepest, it warms quickly in spring. The lake bed gives you two point drop-offs and a sheltered cove to work. Petenwell Lake is the second-largest lake located entirely within Wisconsin.

Petenwell Lake today: water temperature, bite times and the 3-D lake bed

3. Castle Rock Lake

Castle Rock Lake spreads over 16,600 acres of water. You will find it about 5.4 miles east of Adams. It is the Wisconsin River behind Castle Rock Dam. Expect walleye, white bass, crappie and northern pike. At about 35 ft at its deepest, it warms quickly in spring. Castle Rock Lake is Wisconsin's fourth-largest lake, formed within the bed of the former Glacial Lake Wisconsin.

Castle Rock Lake today: water temperature, bite times and the 3-D lake bed

4. Chippewa Flowage

At 14,600 acres of water, Chippewa Flowage is a big lake. It lies about 3.6 miles west of Little Round Lake. It is the Chippewa River behind Winter Dam. Expect muskie. The deepest water is around 92 ft. The lake bed gives you three point drop-offs and two sheltered coves to work.

Chippewa Flowage today: water temperature, bite times and the 3-D lake bed

5. Turtle Flambeau Flowage

At 12,900 acres, Turtle Flambeau Flowage is a big lake. You will find it about 10 miles southeast of Lac du Flambeau. Turtle Dam holds it on the Flambeau River. Muskie, largemouth bass, smallmouth bass and northern pike are the draw. The deepest water is around 49 ft. On the 3-D map the bed has three point drop-offs and two sheltered coves: good places to start. The Turtle-Flambeau Flowage is the seventh-largest lake in Wisconsin by surface area.

Turtle Flambeau Flowage today: water temperature, bite times and the 3-D lake bed

6. Lake Koshkonong

Lake Koshkonong covers some 10,500 acres. The lake is within an easy drive of Janesville (about 10 miles). The fish here are muskie, largemouth bass, smallmouth bass and northern pike. At about 7 ft at its deepest, it warms quickly in spring. Its bed shows three steep ledges and an upper arm worth a first look. Lake Koshkonong, one of Wisconsin's largest inland lakes, averages only about 6 feet deep.

Lake Koshkonong today: water temperature, bite times and the 3-D lake bed

7. Lake Mendota

Lake Mendota is a natural lake of 9,740 acres of water. You will find it next to Maple Bluff. The fish here are northern pike, white bass, walleye and largemouth bass. It goes down to about 83 ft. On the 3-D map the bed has three point drop-offs and an upper arm: good places to start.

Lake Mendota today: water temperature, bite times and the 3-D lake bed

8. Green Lake

Green Lake is a natural lake of some 7,350 acres. You will find it about 22 miles northeast of Oshkosh. The fish here are largemouth bass, smallmouth bass, walleye and northern pike. The deepest water is around 237 ft. Its bed shows three point drop-offs and two sheltered coves worth a first look. At 237 feet deep, Green Lake is the deepest natural inland lake in Wisconsin.

Green Lake today: water temperature, bite times and the 3-D lake bed

9. Lake Wisconsin

Lake Wisconsin spreads over 7,200 acres. You will find it about 21 miles southeast of Madison. Prairie du Sac Dam holds it on the Wisconsin River. Like most lakes its size in Wisconsin, it should hold walleye, northern pike, largemouth bass and smallmouth bass. It goes down to about 24 ft. Its bed shows three point drop-offs and two sheltered coves worth a first look.

Lake Wisconsin today: water temperature, bite times and the 3-D lake bed

10. Beaver Dam Lake

At 6,720 acres of water, Beaver Dam Lake is a good-sized lake. The lake is right by Beaver Dam. Expect largemouth bass, northern pike and walleye. At about 7 ft at its deepest, it warms quickly in spring. The lake bed gives you three point drop-offs and a steep ledge to work. Beaver Dam Lake contains 26 privately owned islands ranging from 0.1 to 2.8 acres.

Beaver Dam Lake today: water temperature, bite times and the 3-D lake bed

Big water, big days

Large lakes make their own weather: a breeze that is nothing on a pond builds real waves over miles of open water. Check the wind on the lake page before you launch and keep to the lee shore when it picks up.