Iguanas are one of the last animals most players tick off, for a straightforward reason: they live in two places, one of which you visit for a single chapter and can never return to. Knowing the Red Dead Redemption 2 iguana location is mostly about knowing which of those two you are still able to reach.
Short answer
Look along the sandy ground and rocks around Rio del Lobo and the southern desert of New Austin, on hot clear days. The other population lives on Guarma, which is a one-time visit — if you missed it there, New Austin is your only option.
The New Austin population
The reliable spot is the arid south-west: the broken rocky ground near Rio del Lobo Rock and the desert flats around it. Iguanas bask on stone in daylight, which makes this the rare hunt that is easier in the middle of a hot, clear day than at dawn.
Walk rather than ride. They are small, they sit motionless, and from horseback at speed they read as part of the rock. Eagle Eye picks them out immediately, and it is worth pulsing it every few steps rather than scanning by eye.
See also: Red Dead Redemption 2 Android — another RDR2 answer people look up right after this one.
The Guarma problem
Chapter 5 takes place on Guarma, an island with its own set of animals, and iguanas are among them. It is also a linear chapter with no way back afterwards. If you want the Guarma species in your compendium, they have to be studied and skinned during that chapter, and the window is short.
This catches a lot of people, because chapter 5 does not feel like a place to go hunting — you are moving through a story, not exploring. The compendium does not care about the difference.
See also: Red Dead Redemption 2 Enhanced Edition — another RDR2 answer people look up right after this one.
Getting a perfect skin
Small animal, small weapon. The varmint rifle with a headshot is the only clean answer; anything with more power ruins the skin regardless of where you hit. Study the animal with binoculars first to confirm the star rating — a two-star iguana cannot produce a perfect skin no matter how good the shot is.
Bait does not help here. Herbivore bait is aimed at grazing animals, and iguanas will not come to it, so the whole hunt comes down to walking the right ground at the right time of day.
See also: Elden Ring Limgrave Map — Elden Ring runs into this one too.
Why the skin matters
Perfect iguana skins feed into trapper crafting, and the species counts toward the hunting challenges and the compendium. None of it is required to finish the game, which is exactly why the iguana ends up as an epilogue errand for most players — by then New Austin is fully open and there is nothing stopping a dedicated afternoon of it.
If you cannot find any
Three things fix most empty searches. Ride out of the region entirely and come back so spawns re-roll. Check the weather — rain suppresses them. And confirm you are actually in New Austin rather than the edge of it; the habitat is narrower than the desert looks on the map, and the rocky ground near the river is where they concentrate.
Red Dead Redemption 2 FAQ
Where is the best iguana location?
The rocks and sand around Rio del Lobo in New Austin, during clear daytime weather.
Can I return to Guarma?
No. Chapter 5 is a one-way visit, and its animals must be studied while you are there.
What weapon should I use?
The varmint rifle, aimed at the head, on an animal you have already studied.
When can I reach New Austin?
Comfortably in the epilogue. Earlier attempts as Arthur are discouraged by the game in ways you will notice quickly.
Walk the rocks in the midday heat with the varmint rifle out, and the animal that seemed missing turns out to have been sitting still in plain sight.