コウ, みさき, さき
headland, cape, spit, promontory
JLPT1 G7 S8 F1972
As per 甲# (press down on) + 山 mountain → mountain gorge (pressed down on by cliffs on both sides). Compare 峽. However, the character has been applied to land jutting into the sea and pressed upon by water on both sides, therefore *cape* or *promontory*.
[Full Kanji Etymology List]