Flat Iron Lake is a large lake located on the eastern borders of the Great Plains region of the West Elizabeth territory.
The lake serves as the game area's eastern border in Red Dead Redemption. The San Luis River flows out from Flat Iron Lake.
In Red Dead Redemption 2, it is located at the center of the five American territories, bordering West Elizabeth, New Hanover and Lemoyne.
Likewise, three regions have borders on the lake, Great Plains and Big Valley of West Elizabeth to the west, The Heartlands of New Hanover to the north, and Scarlett Meadows of Lemoyne to the east. Lannahechee River, Upper Montana River, and Dakota River empties into the lake, which then flows out to San Luis River from the west.
- The Wreck of the Serendipity is located in a shallow inlet of the lake, however, the wreck is only appear in Redemption.
- The lake is a way to cross over to Nuevo Paraíso.
- John Marston arrives in Blackwater at the start of Redemption by using the Morningstar to get across the lake.
- In Red Dead Redemption if the player is too look across the Flat Iron Lake from Blackwater, they can see that Nuevo Paraíso and Lemoyne are bordering eachother.
- In Red Dead Redemption, this location does not count toward 100% Completion.
- In Red Dead Redemption 2, players can find the Tricorn Hat inside the shipwreck in the cove. A lockbox there also contains Aged Pirate Rum.