Issue(s): Sub-Mariner #30
Cover Date: Oct 70
Title: "Calling Captain Marvel!"
Credits:
Roy Thomas - Writer
Sal Buscema - Penciler
Mike Esposito - Inker

Review/plot:
This issue is a nonsensical fight between Namor and Captain Marvel and subsequent team-up. The bad guy of the issue is a random criminal who has happened upon a device (actually a pair of them) that will cause all of the Earth's oceans to become radioactive.

Namor has destroyed the first device prior to the start of this issue, but in the aftermath he acquired amnesia as well as an irrational fear of water.

After the fight...

...Captain Marvel transforms back into Rick Jones so that Rick can make his gig, and Rick brings Namor along. At the concert, we learn that it's become a trend for hippies to wear "Namor ears" since Namor took up the cause of environmental protection.

Rick's apocalyptic folk-rock (predating Current 93 by decades!)...

...causes Namor to freak out and eventually remember the plot, so he and Captain Marvel fly off to take care of business.

This story was probably meant to try to drum up interest in Captain Marvel although it seems oddly timed after the failure of Captain Marvel #20-21 to do the same. Publishing this story before those issues might have worked better, although i'm not sure if Sub-Mariner was the book to do it in at all.

The other possibility is that this story was actually meant for the Captain Marvel book. It does feature a recapped history of Namor, which is a bit odd; you'd think you'd want to provide the background for the guest star, not the main character. But since it's drawn by the Sub-Mariner's regular art team, i'm not sure; i guess Thomas could have just had the script finished.

Update: backing up Mark's comment, the lettercol in issue #34 confirms that this issue was actually meant as a "fill-in" for the Captain Marvel series.

The recap shows what i think is meant to be Giganto, although it's a little off-model and referred to as "Monstro".

Quality Rating: D+

Historical Significance Rating: 1

Chronological Placement Considerations: Namor's appearance in Fantastic Four #102-104 takes place after this issue. This should also take place after Captain Marvel #20-21 since in those issue Captain Marvel says its been a long time since Rick Jones swapped him out of the Negative Zone.

References:

• Captain Marvel and Namor fought before in Captain Marvel #4, but Marv was wearing a different costume at the time, so while CM recognizes Namor, Namor doesn't remember him. No footnote. It's probably best that Namor doesn't remember, since that issue had Marv pinning an attack on Namor.
  
• Assuming that is meant to be Giganto above, it's a reference to Fantastic Four #4.
  
• The only other reference to a specific event in Namor's background recap is the recent confrontation at the United Nations from Sub-Mariner #25. No footnotes for any of the flashbacks.

Crossover: N/A

Continuity Insert? N

My Reprint: N/A