● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 潮の高さ 　　[cm] 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:00 ● ・・・潮位 ・・・砂浜の高さ