Learn Dutch: De zee is te gevaarlijk om in te zwemmen, dus gaat de zwemmer naar huis. - The sea is too dangerous to swim in, so the swimmer is going home.

In Dutch constructions using om ... te plus a preposition (like "to swim in"), the preposition must directly precede te and the infinitive verb. While English leaves the preposition dangling at the end of the phrase, Dutch pairs it closely with the verb to form om in te zwemmen.

Could I say om erin te zwemmen instead of just om in te zwemmen?

Yes, but it isn't strictly necessary. When the subject of the main clause (De zee) is clearly the logical object that the preposition refers to, Dutch frequently drops the er in these om ... te phrases. Saying om in te zwemmen is perfectly idiomatic and avoids sounding cluttered.

Why does the verb gaat come right after dus, triggering inversion?

The word dus (so/therefore) can act as either a coordinating conjunction or an adverb. When treated as an adverb at the start of the second clause, it takes the first position, which means the verb (gaat) must come before the subject (de zwemmer). You could technically treat it as a conjunction and say dus de zwemmer gaat naar huis, but using it as an adverb with inversion is extremely common.

Just as a refresher, why is it naar huis instead of thuis?