Meanwhile, Spider-Man can't sleep so he's swinging around town, bored off his ass. Apparently, a couple of issues earlier, he (as Peter Parker) promised a young lady named Debbie Whitman that he would check in on her uncle for some reason. So he does that.
Turns out his timing is impeccable. Uncle Whitman was getting pushed around by some sailors he hired that no longer want to honour their contract out of fear of what Namor's been doing. So Spidey bails him out.
A chat with aunt May straightens him out, so Spider-Man joins Whitman at sea. The rebellious sailors feel safer with web-head around so they agree to do the job they signed up for.
And once at sea, it doesn't take long for the guest-star to appear.
Spider-Man does take Namor down by keeping him from the ocean to gradually weaken him and webbing up his ankle wings to cause him to crash to the deck.
As they grapple on the deck, Namor explains that the power generators that are being placed in the ocean are messing with Atlantis' own power. This is why he's been wrecking them.
When Spider-Man claims innocence and ignorance of all this, Namor suggest a more productive location for the generators which won't affect Atlantis. As the land-lubbers discuss this, Namor takes off.
Namor showed up again a few issues later, in #214, and that was the first part of a two-parterso for a few months in late 1980, he was a semi-regular character in Amazing Spider-Man.