Underwater fighting full attack

[Hobit of Bree]

Hi folks,
This is mainly about fighting underwater, but it relates to flying too.

If you don't have a swim speed and you aren't on the ground, you make a swim check to see how well you can fight. https://www.d20pfsrd.com/gamemastering/environment/wilderness/terrain/aquat ic-terrain/

Does that swim check for the table entry "Successful Swim check" require a move action?

The "action" part of swim is a lot less clear than fly. http://legacy.aonprd.com/coreRulebook/skills/swim.html

"Action: A successful Swim check allows you to swim a quarter of your speed as a move action or half your speed as a full-round action."

[Jakken]

I interpret the successful swim check as just keeping your balance/moving as you want to, not an actual action. I haven't seen any language that interprets it as an action (no ability to retry the same round, no restrictions on full-round actions etc)

The "Action" section under the skill I take as only if you want to move.

[LordKailas]

Some one was kind enough to put together an underwater combat flow chart.

Based on the chart (re-linked here)

It depends if your bouncy is netural or not (basically, are you being dragged in a direction you don't want to go?). The chart indicates that it takes a move action to make the swim check to maintain your position / not be off balance. If you just let yourself float/sink/ whatever then you can forego the check and just take the penalties for being off-balance instead.