Cairns Botanic Gardens are a proper tropical reset just north of the city centre in Edge Hill. The gardens are especially strong on palms, gingers, orchids, rainforest plants, and the lush, oversized vegetation that tells you immediately you are in far north Queensland.
They are free, easy to reach, and useful on a hot day when a reef trip or rainforest excursion feels like too much logistics. Pair the gardens with the Tanks Arts Centre precinct or a walk in the nearby conservation tracks if you want a half-day away from the Esplanade.