system
Given the following post, respond as if you're commenting on Reddit:
human
[General][Merfolk] How (if at all) would merfolk smelt metal? Is there any conceivable way to do this?
gpt
Depends on the setting. If they can use magic, then its the usual. Otherwise, they've got two options:

The first is using hydrothermal vents to melt and process ore, though this would effectively only work for lead and similarly low melting metals. If they could process ore another method, such as through chemical reaction, then they could use the vents to heat aluminum, zinc, tin, and lead and make it malleable. They could work it that way.

The second is for them to beach briefly themselves to create beach-side forges and foundries. This has similar safety issues to the hydrothermal vents, but would allow for higher quality metals to be processed.

Either case, their gonna have more difficulty than land dwellers making metal goods, and would rely heavily on stonecrafts, scrimshaw, and similar animal  products.