Ramban, Targum Onkelos and Targum Yonasan: 'From the desert the well went with them down to the valleys and from the valleys to the high places'.

Rashbam: 'Matanah', 'Nachaliel' and 'Bamos' are all place-names.

Seforno: The Pasuk implies that in spite of flowing with them to all of these places, the well lost none of its water along the way - an additional facet of its supernatural qualities.

Refer to 21:19:1:2 & 8.

Rashi #1: It means 'to the top of the cliff ¹ that overlooked Yeshimon (a desplate place from the word ?Shemamah?). ²

Rashi #2 (citing Midrash Tanchuma): With reference to the well, which was buried (after Moshe died) in the Sea of Teverya (the Kineret), ³ the Pasuk means that, if someone stands on the cliff of Yeshimon ⁴ and looks down into the sea, he will see something that resembles a sieve - which in fact, is the well of Miriam. ⁵

Rashbam: Refer to 21:18:4:2.

Targum Yonasan: ?And it (the well) was hidden from them within the borders of Mo?av, that looks down opposite Beis Hayeshimon ⁶ ? because they were lax in Torah-study. ⁷

Rashi: Because that is where Moshe died. ¹

Targum Yonasan: Because they were lax in the Mitzvah of Torah-study.

Oznayim la'Torah (in Pasuk 16): Becsuse they now had many streans of water from which to draw.