Countries with three or more uninterrupted sea coasts

Russia is a good answer, although the list you gave with Arctic and Pacific as separate coasts was wrong. The three there are Arctic/Pacific, Gulf of Finland (or Baltic, if you prefer), and Black Sea.

Turkey is a wrong answer. It has two sections, but each have only one continuous coastline. No other country owns part of those coasts to break them up. The fact that the bodies of water off that coast changes from place to place does not change the answer. I thought I’d made this clear with my example of the US and the East and South Coasts.

For Canada, the Atlantic and Arctic are a single continuous coastline.

France and Malaysia.

England would count, if you allow Wales and Scotland as different countries.

There’s something with the premise I don’t really get.

uninterrupted sea coasts

You then list Gibraltar. Sure, I get it. By the same way of thinking, Morocco has three, since it’s interrupted by the Spanish territories Ceuta and Melilla (i.e. Morocco - Ceuta - Mortocco . Melilla - Morocco)?
But you say uninterrupted. And Spain is qualified by interrupting the coastline (Portugal and Gib) . Or, IOW, if a coastline is uninterrupted, it’s indeed continuous.

What is it that I don’t understand here?

You seem to be getting it. The Spanish coast is interrupted by Gibraltar and Portugal. So it has three sections of coast. Those three sections are uninterrupted.

England has two: From the north end of the Welsh border clockwise to the Scottish border, and from the south end of the Welsh border counterclockwise to the Scottish border.

The United Kingdom also has two: One for Geat Britain and one for Northern Ireland.

Disregard

Low-hanging fruit:

Japan
Indonesia

France

Added — France’s coastlines are broken by Spain and Monaco.

How is Japan included? Where are its coastal breaks?

I don’t think so - I thought Indonesia was a candidate thanks to the borders within Borneo but it isn’t - Malaysia is though on Borneo, just. On TImor-Leste the count for Indonesia is only 2.

Japan doesn’t have any land borders. China used to count for this, before it unified with Macau and Hong Kong. Canada also used to, thanks to the mainland part of the colony of Newfoundland.

This is one problem with the OP: what is a country?

ISO 3166 is one list of countries ➜ https://en.m.wikipedia.org/wiki/ISO_3166-1#Codes ■ ; and the USA has this list ➜ https://history.state.gov/countries/all

Bhutan is in 3166 but is not recognized by the USA.

Russia actually has 4 thanks to Kaliningrad!

Kaliningrad is a city not a country.

Do you want to think about this a bit more, or rather look at a map?

Kaliningrad Oblast?

What’s your question?

Wait, sorry, it’s an exclave, ignore me.

So far we have at least 4.

France — coasts are broken by Spain, Monaco
Saudi Arabia — coasts are broken by Yemen, Qatar
Russia — coasts are broken by Finland, Estonia/Latvia/Lithuania
Spain — coasts are broken by Portugal, Gibraltar

Malaysia as well, on Borneo broken by Indonesia and the 2 parts of Brunei.