For ambience read: atmosphere, meaning: a surround or envelope of selected data = stressors.
An ambience can become a bath when the brain and body are wholly flooded, i.e. filled, indeed, overwhelmed exclusively with the ambience’s data = stressors.
The stressors that impact as ‘bath’ are (fundamentally random, but normally weakly relativised) sights, sounds, smells, tastes and touches, all generated (from streams of actual data bits accessed externally or internally interpreted) as virtual realities inside the brain operating as Biological Navigation System (to wit: Bio-Nav). Any stressor or combination of stressors, positive or negative, may flood (i.e. load to capacity and thereby make real) current consciousness, that is to say, the display (or map, as iconic representation, that is to say, the self-image selections currently displayed) of a bio-system’s state (as whole survival (i.e. self-preservation) response).
In addition to forest ambience, the affects of exercise, like walking or climbing, or selective daydreaming also positively stress and flood the bio-system and so help return to maximum survival response capacity.