While the legal status of downloading ISOs for games you do not own remains a gray area to strictly prohibited, the preservation community has found other avenues. Archives on the Internet Archive or private Discord communities dedicated to PSP preservation have largely taken the place of public sites like Emuparadise.
The most complete English patch for MHP3rd was created by (later updated and maintained by Hatsuu, known for the Trails from Zero fan translation). It translates:
An ISO file is a type of file that contains a copy of the game's data, which can be used to play the game on an emulator or on a console with a modded firmware. EmuParadise is a popular website that provides ISO downloads for various games, including PSP titles like "Monster Hunter Portable 3rd".
The keyword "Emuparadise" in the search query is a nod to what was once the titan of retro gaming downloads. For over a decade, Emuparadise was the go-to repository for ROMs and ISOs. It was widely considered the safest and most reliable source for files like the MHP3rd ISO.
Because there was no official English release, the community took matters into their own hands. A group of dedicated fans created an unofficial English translation patch. This patch translated the critical menu items, weapon names, and quest descriptions, making the game playable for those who did not read Japanese.