The park complex ends at a train station, from which a train runs every half-hour to the Cataratas train station, where the waterfall walks begin, and to the Garganta del Diablo. Overcrowding is a serious problem in peak periods and you may have to wait a long while for a spot. Seek out a printed return ticket as soon as you arrive. You may prefer to walk: it’s only 650m along the Sendero Verde path to the Cataratas station, and a further 2.3km to the Garganta, and you may well see capuchin monkeys along the way.
To see all the falls involves quite a lot of walking although you'll have many breaks as you gawk at individual cascades, and there are not many strenuous climbs.
Most of the trails are at least 90% wheelchair/pusher accessible; while there are some stairs in parts it's possible to reach all the viewpoints by navigating some of the trails in reverse or using dedicated special access paths.