潜降 is read as せんこう (senkou) and means diving.
せんこう
senkou
せんざい
potentiality
せんすいかん
submarine
ひそむ
to lurk
くぐる
to dive (into or under the water)
せんぷく
concealment
せんにゅう
infiltration
せんすい
diving
underwater navigation
せんざいいしき
subconsciousness
submarine voyage
もぐりこむ
to sneak into
もぐり