The Rinax marshlands were a region on the moon Rinax, near where Neelix grew up.
The summers in the marshlands were the hottest in the sector. Conditions included temperatures of 50° Celsius, with a 90 percent humidity, and some of the most vicious lavaflies on Rinax. Things were even worse here then in other hot places like Indiana because there were three suns. (VOY: "Macrocosm")
However, in 2355, Rinax fell victim to a metreon cascade, which wrecked the entire moon's ecosystem, including the marshlands. (VOY: "Jetrel")