Seljalandsfoss, Skógafoss, Gullfoss,... Iceland is beautifully confusing. To me, Seljalandsfoss translates to “the tall waterfall you can walk behind”.
One thing about Iceland and most of its sites is that it has become incredibly touristy, even waking up at dawn doesn’t guarantee you will be the only soul there. So my tip is, embrace it and be considerate of other people, after all we are all tourists! Don’t let it take away from your experience.