If you're in the mood for salty breezes and treasure maps, here's the good news: I found that 'Treasure Island' is widely available as a free PDF because the original novel (published in 1883) is in the public domain. That means the plain text by Robert Louis Stevenson can be legally distributed for free in most countries, and projects that digitize classics—like Project Gutenberg—offer clean, downloadable PDFs and EPUBs. I usually grab the Project Gutenberg edition (their files are reliable and unadorned), but you can also find versions on the Internet Archive, Google Books, ManyBooks, or Standard Ebooks if you want a nicer typographic edition.
One caveat I always tell friends: illustrated, annotated, translated, or newly edited versions may carry separate copyrights. So while the core text of 'Treasure Island' is free, a modern edition with fresh illustrations or a new introduction might be sold by a publisher. If you want an old-school, no-frills read, stick with plain public-domain editions. For audiobook fans, Librivox has free public-domain recordings if you prefer listening while drawing the map on a napkin.
A practical tip from my own routine: avoid sketchy download sites that bundle malware; stick to well-known archives or your local library's digital lending app (OverDrive/Libby). I still love following Jim Hawkins on his voyage, and reading a pocket PDF on my phone while commuting has been pure nostalgia—try it and picture the Hispaniola slicing through a gray sea.