Are biodegradable burial urns a good option for cremains?

My dear father has left us and his memorial is coming up soon. I am on the search for our father's final home. I just don’t know whether a casket or an urn would be suitable. He enjoyed being out in nature, so I was thinking of getting him a wooden urn, but my sister thinks an environmentally friendly one would better reflect the kind of person he was. I’m a bit inexperienced when it comes to shopping for urns.