Translation 1: strangely dynamic translation of ἐσβάντες. But, since the student needs to focus on τὰς ναῦς for the exercise, "threw themselves" can be ignored or skimmed over. On the other hand, preposition can be explained in detail.

ἐς into τὰς their ships ναῦς their ships ἐσβάντες threw themselves threw ἐσβάντες themselves ἐσβάντες into ἐς their τὰς ναῦς ships τὰς ναῦς