This is a copy of "Sub-Mariner", issue #52, published by Marvel Comics in August 1972 as part of their 1968 publishing run.
This copy has been bagged and boarded since purchase and in a controlled environment ever since.
Series - Sub-Mariner (1968 Marvel)
Issue - 58
Date Published - August 1972
Publisher - Marvel Comics
Page Count - 36
Story - Bill Everett and Mike Friedrich
Art - Bill Everett
Cover - Gil Kane and Joe Sinnott
From the MyComicShop description:
"Namor travels to the surface world with Namorita in search of Betty Dean who he hopes will serve as a guardian to the young Namorita; They track down Betty who is vacationing on the Japanese island of Krakinowa; Namor stumbles upon a hidden city controlled by the Dragon-Lord who is eager to bring about another war with the US; The Dragon-Lord sends his agent, Sunfire, off to capture a US freighter; Namor intercepts Sunfire as he's concerned that the destruction of the freighter could threaten the health of the seas; Despite Namor's best efforts, Sunfire strikes a deadly blow against the freighter and it begins to sink."