"I find that very interesting."
Translation:Das finde ich sehr interessant.
What you are trying to say here is "It is very interesting to me." This has the same basic meaning. But we have to be careful in translating the English "to". What does "to" actually mean here and how would it be said in German?
This sentence could also be said: It is very interesting for me. Es ist sehr interessant für mich. And the super simple version: It interests me. Es interessiert mich.
These are both accusative, not dative.
I think anything that takes the form: It is to me. Is going to use "für" and take the accusative pronoun.