![](http://www.ecns.cn/hd/2021/07/22/98e85c87a8854d52868a989228c53e70.jpg)
People take boats to visit the Blue Grotto (or the Blue Cave), a scenic spot in Croatia's Bisevo, on July 19, 2021. The entrance of the cave is 1.6-meters-high and 2.5-meters-wide, whereas the inside reaches 12 meters deep and 15 meters high. The cave was formed by the sea waves. (Photo/ IC)
![](http://www.ecns.cn/hd/2021/07/22/53e03acda0474f0e9c711635a81f705e.jpg)
People take boats to visit the Blue Grotto (or the Blue Cave), a scenic spot in Croatia's Bisevo, on July 19, 2021. The entrance of the cave is 1.6-meters-high and 2.5-meters-wide, whereas the inside reaches 12 meters deep and 15 meters high. The cave was formed by the sea waves. (Photo/ IC)
![](http://www.ecns.cn/hd/2021/07/22/3f7cfba62fe54bfd959ff98840649620.jpg)
People take boats to visit the Blue Grotto (or the Blue Cave), a scenic spot in Croatia's Bisevo, on July 19, 2021. The entrance of the cave is 1.6-meters-high and 2.5-meters-wide, whereas the inside reaches 12 meters deep and 15 meters high. The cave was formed by the sea waves. (Photo/ IC)