Paddle boarding on Lady Bird Lake is a fun activity for a Saturday afternoon. Texas Rowing Center is where we have rented paddle boards in the past and there is a spot near the bridge (South congress ? South Lamar?) where people gather and chill (more shallow there). Highly recommend!
Barton Springs is a natural spring that is a whopping 68 degrees year round. I believe it costs around $5 for non-locals to get into the pool-side, but you can also venture to the free side which I have no idea how to explain how to get to. Definitely an Austin staple
It is a big park. Not more to say. Can have a picnic or do what people do at parks.
Big brewery with good pizza. Has live music sometimes and is a fun space.
Lots of shops and the I love you so much wall. Good spot for people who like to walk/shop/be touristy