About an hour from Takamatsu is Tokushima 徳島, well-known for the Awa Odori Dance Festival in August every year and Naruto whirlpools. Tourists can get a taste of the dance at the Awa Odori Kaikan, 15 mins walk from JR Tokushima station.
To view the Naruto whirlpools, you may take a bus from Tokushima to Naruto Koen 鳴門公園(about 1 hour JPY690 non-JR) or take a 40 min JR train ride from Tokushima to Naruto station followed by a 20 min bus ride (JPY300) to Naruto Koen (This is the same bus as the one from Tokushima to Naruto Koen. It passes by JR Naruto station). Do ask the tour info (opposite the bus terminal) for a bus time table before departing.
From Naruto Koen, go up the steps toward Uzu-no-michi渦の道, a passageway under the Onaruto bashi大鳴門橋, 45 m above the whirlpools, with glass windows on the ground where you can view the action. A combination ticket which includes entrance to the passageway and a Uzushio boat ride (JPY1750) may be purchased at uzu-no-michi. Do check tide times before going as the optimal times for viewing the whirlpools are during low and high tides. Uzu-no-michi also displays the tide times. Allow half an hour for a walk through uzu-no-michi.
We met a really nice lady at the uzushio boat station who offered to help us call the restaurant at JR Naruto station to remain open for us because by the time we reach, they would have been closed.