Había mar picada; total, que descansamos.

Había is the imperfect of haber, and here it means there was / there were.

Spanish often uses the imperfect for background circumstances or ongoing conditions:

• Había mar picada = The sea was rough / There were rough seas

Why not hubo?

• Hubo usually presents something as a completed event, not as a background situation.
• Here, the rough sea is the situation that explains what happened next, so había sounds natural.

Why not estaba?

• You could say El mar estaba picado, but that is a different structure:
  • Había mar picada = literally something like there were rough sea conditions
  • El mar estaba picado = the sea was rough

So había is used because the speaker is setting the scene.

Mar picada means rough sea, choppy sea, or rough sea conditions.

It refers to the state of the sea when there are noticeable waves and the water is not calm. It is a common expression in weather reports, sailing contexts, and everyday speech in Spain.

So:

• Había mar picada = The sea was rough / It was choppy at sea

It does not mean that the sea was literally bitten or chopped. Here picada is part of a fixed expression about sea conditions.

Good question. Mar is usually masculine in general Spanish:

• el mar

But it can also be feminine:

• la mar

In expressions about sea conditions, especially in traditional, nautical, or meteorological usage, you will often see the adjective in the feminine:

• mar picada
• mar calmada

So although mar is usually masculine in many contexts, mar picada is a standard set expression.

You may also hear:

• El mar estaba picado

So both patterns exist, but in this sentence mar picada is a fixed and natural phrase.

Because the structure is:

• haber + noun phrase
• Había mar picada

With haber meaning there is/there was, Spanish often leaves out the article when talking about the existence of something in a general way.

Compare:

• Había niebla = There was fog
• Había viento = It was windy / There was wind
• Había mar picada = There were rough sea conditions

If you say:

• El mar estaba picado

that is a different construction, where el mar is the subject.

Here total is a discourse marker, very common in Spain. It does not mean total in the mathematical sense.

In this kind of sentence, it means something like:

• so
• anyway
• the upshot is
• in the end

So:

• Había mar picada; total, que descansamos.
• The sea was rough, so/in the end we rested.

It helps the speaker move from the situation to the conclusion or result.

In colloquial Spanish, especially in Spain, total, que... is a very common way to introduce the result or conclusion of a situation.

It works a bit like:

• so...
• and so...
• the result was that...

Examples:

• Perdimos el autobús; total, que llegamos tarde.
  We missed the bus, so we arrived late.
• Empezó a llover; total, que nos fuimos a casa.
  It started raining, so we went home.

So in your sentence:

• total, que descansamos = so we rested / anyway, we ended up resting

This is fairly informal and conversational.

Because it refers to a completed action:

• descansamos = we rested / we had a rest

The sentence first gives the background:

• Había mar picada = ongoing situation

Then it gives the action/result:

• descansamos = completed action taken because of that situation

This contrast is very common in Spanish:

• imperfect for background
• preterite for the main event

So the tense choice is very natural:

• background condition: había
• resulting action: descansamos

You could, but it would change the meaning.

• descansamos = we rested / we ended up resting
  This sounds like a complete action or decision.
• descansábamos = we were resting / we used to rest
  This sounds ongoing, descriptive, or habitual.

In this sentence, the idea is:

• the sea was rough
• as a result, we rested

So descansamos is the better fit.

It is mostly informal or neutral-colloquial. It is very common in spoken Spanish in Spain and in informal writing.

In more formal Spanish, you might prefer connectors like:

• así que
• por lo tanto
• de modo que
• por eso

For example:

• Había mar picada, así que descansamos.

That is more straightforward and works in almost any context.

The semicolon separates two closely related parts:

• Había mar picada
• total, que descansamos

It shows a pause stronger than a comma, but not as strong as a full stop.

In everyday writing, many people might also write:

• Había mar picada, total que descansamos.
• Había mar picada. Total, que descansamos.

So the semicolon is mainly a punctuation choice that helps show the link between the situation and the conclusion.

Not very naturally.

A word-for-word version would be something like:

• There was rough sea; total, that we rested

That is not idiomatic English.

A natural translation would be:

• The sea was rough, so we rested.
• It was rough at sea, so we took it easy.
• There were rough sea conditions, so we rested.

This is a good example of where you should understand the expression as a whole, not translate each word literally.