
Here are the things I like about this magazine, especially compared to Skin Diver magazine (SDM), its main competitor at the time:
Here are the things I don't like about Dive:
These latter attributes may have contributed to the demise of this magazine. Interestingly, even decades later these same drawbacks that kept me from wanting to subscribe in the 1960s still prevent me from really getting heavily interested in this magazine. It was simply a more recreational, relaxed magazine meant more for show than depth. Whereas SDM had great news, fascinating adventures, good technical information, futuristic predictions, political activist articles, and so on, Dive just had fun articles about ladies, fictional stories, a heavy emphasis on The Diving Locker of San Diego, a heavy emphasis on specific trips rather than general info for the public, and so on.

I have seen Dive issues advertised with dates from 1964-1979, so for the time being I'm assuming this 15-year span is close to the actual span of this magazine.
Clearly, even Dive magazine itself had some numbering problems:
| month & year shown on cover | month & year shown inside | vol. & no. shown inside | vol. & no. probably intended | month & year probably intended |
|---|---|---|---|---|
| Aug.-Sept. | (c) 1964 | (none) | . | August-September 1964 |
| Oct.-Nov. | (c) 1964 | (none) | . | October-November 1964 |
| June | (c) 1964 | (none) | . | June 1965 |
| October 1967 | October 1967 | 1, 1 | 1, 1 | September-October 1967 |
| December 1967 | (none) | 1, 2 | 1, 2 | November-December 1967 |
| February 1968 | January-February 1968 | 1, 3 | 1, 3 | January-February 1968 |
| April 1968 | March-April 1968 | 1, 4 | 1, 4 | March-April 1968 |
| June 1968 | May-June 1968 | 1, 5 | 1, 5 | May-June 1968 |
| August 1968 | July-August 1968 | 1, 6 | 1, 6 | July-August 1968 |
| October 1968 | September-October 1968 | 2, 1 | 2, 1 | September-October 1968 |
| December 1968 | November-December 1968 | 2, 2 | 2, 2 | November-December 1968 |
| . | . | . | 2, 3 | January-February 1969 |
| April 1969 | March-April 1969 | 2, 4 | 2, 4 | March-April 1969 |
| June 1969 | May-June 1969 | 2, 5 | 2, 5 | May-June 1969 |
| . | . | . | 2, 6 | July-August 1969 |
| . | . | . | 3, 1 | September-October 1969 |
| . | . | . | 3, 2 | November-December 1969 |
| . | . | . | 3, 3 | January-February 1970 |
| April 1970 | March-April 1970 | 3, 4 | 3, 4 | March-April 1970 |
| June 1970 | May-June 1970 | 3, 5 | 3, 5 | May-June 1970 |
| August 1970 | July-August 1970 | 3, 5 [sic] | 3, 6 | July-August 1970 |
| October 1970 | September-October 1970 | 3, 6 [sic] | 4, 1 | September-October 1970 |
| . | . | . | 4, 2 | November-December 1970 |
| February 1971 | January-February 1971 | 4, 3 | 4, 3 | January-February 1971 |
| April 1971 | March-April 1971 | 4, 4 | 4, 4 | March-April 1971 |
| . | . | . | 4, 5 | May-June 1971 |
| . | . | . | 4, 6 | July-August 1971 |
| October 1971 | September-October 1971 | 5, 1 | 5, 1 | September-October 1971 |
| December 1971 | November-December 1971 | 5, 2 | 5, 2 | November-December 1971 |
| February 1972 | January-February 1972 | 5, 3 | 5, 3 | January-February 1972 |
| April 1972 | March-April 1972 | 5, 4 | 5, 4 | March-April 1972 |
| June 1972 | May-June 1972 | 5, 5 | 5, 5 | May-June 1972 |
| August 1972 | July-August 1972 | 5, 5 [sic] | 5, 6 | July-August 1972 |
| October 1972 | September-October 1972 | 6, 1 | 6, 1 | September-October 1972 |
| December 1972 | November-December 1972 | 6, 2 | 6, 2 | November-December 1972 |
| February 1973 | January-February 1973 | 6, 3 | 6, 3 | January-February 1973 |
| April 1973 | March-April 1973 | 6, 4 | 6, 4 | March-April 1973 |
| June 1973 | May-June 1973 | 6, 5 | 6, 5 | May-June 1973 |
| August 1973 | July-August 1973 | 6, 5 [sic] | 6, 6 | July-August 1973 |
| October 1973 | September-October 1973 | 6, 6 [sic] | 7, 1 | September-October 1973 |
| January 1974 | (none) | 7, 2 | 7, 2 | January 1974 |
When the above numbering problems are corrected, the situation makes sense from 1967 on. It appears that the (bimonthly) issues were numbered 1-6 across the span of one year, and that the starting month for each number "1" was not January but rather October.
Circa 1964, the situation is still unclear to me. For example, in one issue with only "June" marked on the cover, the only official date shown inside on the contents page is (c) 1964. However, on several pages in that issue are references to 1965 and none to 1964: "HAVE YOUR TANK V.I.P.'ed 65.", "RENT 1965 Chris-Crafts", "DIVE MAGAZINE & NASDS AWARD ... APRIL 1965", so that issue was probably June 1965, and possibly the (c) 1964 date refers to the earliest issue of Dive. But that June issue indicates no pairing of months, and worse, June is out of sync with all the other issues of Dive, before and after 1965.
The Vol. 1 No. 1 issue carries an explanation on an opening page that the magazine had run into temporary financial problems and had discontinued for an unspecified amount of time, but was fortunately able to restore publication, which was an unknown precedent in the diving magazine business. Such financial problems would account for the irregularity of issues and their numbering, at least in the pre-1967 issues.

Starting in August 1968, the covers had a diver flag symbol placed to the left of the magazine title, a practice which continued after the logo changed, and ever after, as far as I can tell.

The "DIVE" logo itself changed significantly between 1970 and 1971. The original 4-dot Dive logo that I knew so well from the late '60s ended in either October or December 1970, and was replaced with a new logo without the dots by February 1971. I don't remember this less distinctive logo, only the earlier 4-dot logo. SDM went through several such logo changes, also.

In June 1973 the size of Dive magazine was reduced slightly in its vertical dimension. Issues from that month on will fit vertically onto a scanner, but still are too wide to fit horizontally completely on a scanner. SDM went through a similar reduction in size in the 1950s.
Did Dive become monthly later on? I have only one issue from 1974, so I can't be certain, but that issue is for January 1974, which is the first pure January issue up to that time. Until then January was always skipped or combined with February. Since Dive seemed to be copying Skin Diver in many ways such as size reduction, logo changes, and addition of well-known authors, I think it's quite likely Dive had been pushing to be a monthly magazine for years, and finally achieved that in 1974.