The Agamon Hahula park is in the heart of the Hula valley. If you love birds, this is one of the best places for bird watching and just nature observing in general. Even if you are not a bird enthusiast, this place is awesome. There is a 8 km trail around the lake. You can rent bikes and take the trail - which is pretty flat - along beautiful shady areas and enjoy the nature. And of course the birds.
Other options here - a safari wagon, a ringing station where you can learn about the research being done on site. And super cool - a night tour of nightlife in the area. Do this in the warmer months.