If a region is generally peaceful at the macro scale, then there's less need to ramp up military might. Notice that North America didn't really develop nations OR naval armadas prior to the forming of USA. They had fishing and trade, though. They also didn't develop large armies, either, so there's that...
Materials or Skills?
If your nation doesn't have access to the raw materials necessary to build a navy, they may not have a maritime affairs focus. If you can't build ships, then you don't need a navy. This could be because you lack the lumber, or because you lack the know-how to build a competitive naval force.
Low population density
If your population density is low, you're less likely to need to expand. It takes land to support a growing population, and sometimes it's easier to take someone else's land than to continue clearing and maintaining your own.
A local religion may have strictures against oceanic travel, or against the concept of "big government" that would meddle in naval affairs. Or there could be some sort of perceived rule against the sea, so only a few people are brave/foolish enough to attempt oceanic interactions beyond near-shore fishing. If that taboo extends throughout the nobility, then they wouldn't even consider forming a naval affairs group.
There are various reasons your nation might have a treaty-based ban on naval affairs. Maybe they lost a major naval war and the treaty was all that preventing them being wiped out. Or maybe they and another powerful nation signed some mutual protection pact that said they would have no naval powers as their part of that agreement (Cold War type bans on naval warfare, or maybe your nation supplies ground troops and theirs supplies naval forces...)
Maybe your nation is so advanced, relative to their neighbors, that they don't need naval affairs. Or so far behind their neighbors that having a naval affairs division would be utterly pointless. Maybe, via technology or magic, they skipped ocean travel entirely and went "straight" to planes or dirigibles. After all, a floating/flying aerial vehicle is more useful than one trapped on the water.
Perhaps your nobility is too busy stabbing each other in the back (literally and/or figuratively) to form a cohesive naval power. Maybe they're too clanish to focus their energy together towards building a navy.
Here there be dragons. Or Kraken. Or some other beast that has a taste for anything large enough to represent ships of the line.
Building a naval affairs requires money. Maybe your nation simply cannot afford to do so.
If the oceans are too shallow or there aren't enough natural harbors, you may never develop the larger ships like we see during the height of the Age of Sail. Likewise, if wind patterns are wrong, your nation may not be positioned to launch a strong naval vessel — winds too week, or to strong but blowing inland off the sea for example. Or maybe the nation is too far north or too equatorial — people just don't have the temperature range they need to handle ocean voyages on a major scale.
Type of government
If they are a corporatocracy or ruled by guilds, the guild factions may prefer to keep the naval powers to themselves and away from rival corporations/guilds.