Hi there!
Google Keyword Planner can help discover new keywords based on your existing, top-performing keywords to expand your reach effectively. Here’s what the planner suggests for yours:
best outdoor activities in [city]
fun outdoor activities in [city]
best outdoor things to do in [city]
outdoor family activities [city]
outdoor fun in [city]
fun outdoor things to do in [city]
best outdoor things to do in [city]
[city] adventure activities
You might also consider running your best performing keywords on Broad Match (as well as Exact Match) if you’re not already doing that, which would expand the reach by matching to a wide array of similar search queries. You’ll just want to keep an eye on the search queries those yield to ensure they’re relevant to your business. Also make sure to set an appropriate budget for experimenting there as they can potentially spend quickly.
Hope that helps!