おもしろそうに およいでる

[themonk]

Sensei:
I understand the part for ''interesting" and "swimming," but not the ending part in bold.

I suspect that they are grammar related. Any idea?
おもしろそうに　およいでる

This line is from the Koi song.

[Hyperworm]

These two forms are
1. the そう form of 面白い turned into an adverb with に (overall meaning and why そう is used)
2. the te-form of 泳ぐ, + いる (てる/でる is a casual contraction of ている/でいる)

[themonk]

@Hyperworm Sensei:
Thank you.