open sea, offing, rise high into sky
沖 centers on open water away from shore: the offing or open sea. The sense of rising high into the sky extends this idea of being far out and elevated.
沖 combines 氵 (water) with 中 (middle), suggesting water that is far out or in the middle of the sea. The 'rise high' meaning may come from an extended sense of being far out and elevated.
Water 氵 in the middle 中 of nowhere: imagine the open sea far from land, where the horizon rises high into the sky.
For チュウ, picture a boat in the open sea choosing a direction: choose -> チュウ, and the water stretches endlessly around.
Okinawa (city, prefecture)
open sea
off the coast; offshore; out at sea
krill; euphasiid (any species in the family Euphausiacea)
Okinawa Electric Power Co., Inc.; OEPC
Sumatra-Andaman earthquake (2004, resulting in the Indian Ocean tsunami)
Battle of the Philippine Sea (June 19-20, 1944)
Naval Battle off Malaya (December 10, 1941)
Battle of Leyte Gulf (October 23-25, 1944)
Sanriku offshore earthquake (esp. June 15, 1896, March 3, 1933, and March 11, 2011); Sanriku earthquake
staying in Okinawa; resident in Okinawa; stationed in Okinawa
US troops stationed in Okinawa
coming to Okinawa; visit to Okinawa
Tōhoku earthquake (March 11, 2011); Tohoku earthquake; Sendai Earthquake; Great East Japan Earthquake
to rise up into the air; to ascend into the sky
of the ocean; in the open sea; oceanic
Okinawan pachinko parlor slot machine
longshoreman; stevedore
offshore trawl fishery
offshore fishing industry