A couple of the swimming animations of Kirk and Spock were trace overs of the swimming animation of Aquaman (1967) from the late 1960s Filmation show. This is why Spock frequently seems to be drawn as smaller than Kirk.
The Enterprise crew encourage half the planet's population to stop living underseas, and to colonize the surface. This major cultural change to the aquatic species shows a total disregard for the non-interference "Prime Directive" central to Starfleet.
Since the small boat or "scouter gig" used in the search for Kirk and Spock obviously has no flight capability, it had to have been beamed down. This confirms that "Enterprise" has the cargo transporter shown in Franz Joseph's "Enterprise" blueprints.
Although the Aquashuttle is never mentioned by name, it is generally accepted that it is designated the "Cousteau" after the famous oceanographer. Since Jacques-Yves Cousteau designed a number of his own submersibles, it has been suggested by fans that one of his descendants may have had a hand in the shuttle's design.
This takes place in 2269.