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Not so much a guide but if you're like me after playing the first playthrough and realised you've made an error on this by not doing it in the first place. You can reset progress in the settings and unlock the islands by scrolling to the whirlpools (where the islands usually would be) and unlock the islands. All you need to do is collect all the orbs for each island again (which does mean collecting the stars again).

You don't need to collect the photos / maps for this particular achievement but would recommend doing so if you're missing the other achievements.