More Discussions for this daf
1. Rabah in the bathtub 2. Last Section of Agadah 3. Rabbi Shimon and Muktzah
4. Measuring a barrel 5. Rabbah bar Rav Huna's answer on final daf 6. Ending
7. The last five lines 8. Siyum for Meseches Shabbos 9. Measuring on Shabbos

Levy van Leeuwen asked:

what was rabba bar rav huna sitting in a bathtub for on shabbos?

The Kollel replies:

It is Mutar to take a cold bath on Shabbos (see Shulchan Aruch 326:1).

(Furthermore, perhaps he was an "Istanis" and needed to bath in cold water.)

Be well!