Question Best Day Hikes from Reykjavik Without a Car?

I’m curious what you think about day hikes to access without a car from Reykjavik. I will be based in the city for a week and want to explore some of Iceland’s famous landscapes, but I won’t have a car. Are there any good hiking trails that are easy to reach by public transport or tours? I’m looking for something that’s not too challenging but offers great views. Any recommendations or tips would be super helpful!