Yui-Shiori
An undersea walk through unusually clear water by glass-bottom boat
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An undersea walk through unusually clear water by glass-bottom boat

About this spot

A few minutes by car from Osuna Beach (大砂海水浴場), the waters around Takegashima (竹ヶ島), a small island lying off Shishikui (宍喰), are known for clear seas where coral grows in colonies and are designated a marine park. Board a glass-bottom boat and you can watch colourful fish and coral up close through the glass hull, enjoying a tropical undersea walk without even swimming. It is a luxurious way to spend the time before a day at the beach: peering into the sea first. The trip lasts about 20 to 30 minutes, so it is easy to enjoy even with small children.

Season & hours

Name: 大砂海水浴場

Date & time: 7/18 (Sat)–8/23 (Sun) 9:00–17:00

Venue: 海陽町・大砂海水浴場

徳島県海陽町の宍喰エリアに広がる大砂海水浴場は、2026年は7月18日(土)から8月23日(日)まで開設され、遊泳時間は9時から17時までです。料金は無料で、駐車場100台に加え、更衣室・シャワー・トイレも整っており、着替えや水遊び後の身支度に困りません。遠浅の砂浜は波が穏やかで、波打ち際での水遊びから砂のお城づくりまで、小さな子ども連れでも安心して楽しめます。竹ヶ島海中公園や道の駅めぐりの締めくくりにふさわしい、この1日のクライマックスです。

Tips

遊泳時間は17時までなので、着替えの時間も見込んで15分前には切り上げるのがおすすめです。夏の砂浜は日中とても熱くなるため、ビーチサンダルは必携。無料の駐車場は100台分ありますが、週末や夏休み期間は早めの到着が安心です。

Source: kaiyo-kankou.jp

Tips

The boarding point is around Shishikui Fishing Port (宍喰漁港), and the number of sailings varies with the season and weather, so checking in advance is recommended. Sailings may be cancelled depending on sea conditions, so build some slack into your schedule. The sun is strong, so do not forget a hat and sunscreen even on board.

Best time to visit

In the calm morning hours the water is clear and easy to see into, and it photographs well

Access & map

〒775-0513 Takegashima, Shishikuiura, Kaiyo Town, Kaifu District, Tokushima Prefecture (徳島県海部郡海陽町宍喰浦竹ケ島 字竹ヶ島)

Model course featuring this spot

2026 Osuna Beach (大砂海水浴場) Full-Day Course

Tokushima

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An undersea walk through unusually clear water by glass-bottom boat (Tokushima) | Things to Do & Highlights | Yui (栞)