Will it be obvious how to get to the bonus dungeons after completion of the game? Do I have to do anything specific to access themÉ

Thanks.

Rob

Each of the main dungeons have key items (tablets) on last floor of them, which are placed in random places. You need to collect them all in order to access one of bonus dungeons. None of those tablets can be missed forever.

I didn't see any other specific requirements for other bonus dungeons (though I am not yet at the point of doing them).