The query names the people. Something to do with children, an activity for a group of friends or a day out for a family visiting is how these searches are phrased, and pages built around those combinations match them precisely.
The word beginner appears everywhere. Adding it signals that somebody is worried about the level, so an activity page that answers what is required before anything else converts the visitor who would otherwise keep looking.
Half of this is booked the same morning. A forecast changes, a plan collapses and somebody looks for anything available today, so a company that can answer availability immediately takes bookings the rest of the market never sees.
Limits stop more bookings than price. Minimum ages, height and weight restrictions and whether a non-swimmer can take part are checked before anything else, and a page that hides them produces a refund at the meeting point.