Learn Hardcore Finnish: En halua lähteä uimaan syömättä mitään. - I don’t want to go swimming without eating anything.

Because the person is already shown in en, the pronoun minä is normally left out: En halua... instead of Minä en halua.... Both are grammatically correct, but the shorter one is more natural here.

Why is the verb haluta in the form halua, not haluan?

In a negative sentence, the negative verb (here en) carries the personal ending, and the main verb appears in a special connegative form, without any personal ending.

So:

Positive: Haluan lähteä. – I want to leave.
Negative: En halua lähteä. – I do not want to leave.

The connegative form for haluta is halua (no -n at the end).
Using en haluan would be ungrammatical in standard Finnish.

What exactly does lähteä uimaan mean, and why use lähteä here?

Lähteä literally means to leave, to set off, to depart.
The structure lähteä + verb in -maan/-mään means to set off in order to do something.

So:

lähteä uimaan ≈ to go (off) to swim / to go (off) swimming

Using lähteä emphasizes the moment of leaving from where you are now and heading towards some activity (here, swimming). It is very common with activities:

lähteä ostoksille – to go (off) shopping
lähteä lenkille – to go (off) for a run / jog
lähteä ulos syömään – to go out to eat

What form is uimaan, and why not just say lähteä uida?

Uimaan is the illative form of the MA-infinitive of uida.

Very roughly:

Verb: uida – to swim
MA-infinitive base: uima-
Illative ending: -an
→ uimaan

The pattern (movement verb) + MA-infinitive in illative (-maan/-mään) expresses going/coming in order to do something:

mennä syömään – go to eat
tulla katsomaan – come to see
lähteä nukkumaan – go off to sleep

So lähteä uida is not idiomatic Finnish; the natural form is lähteä uimaan.

What form is syömättä, and what does it literally mean?

Syömättä is the abessive form of the MA-infinitive of syödä (to eat).

Very roughly:

Verb: syödä – to eat
MA-infinitive base: syömä-
Abessive ending: -ttä / -ttä
→ syömättä

The abessive means without (doing), so syömättä means without eating / without having eaten.

It works like an adverbial modifier that tells under what condition or in what way something happens:

Lähdin töihin syömättä. – I left for work without eating.
He menivät nukkumaan peseytymättä. – They went to sleep without washing.

Why do we also need mitään after syömättä? Doesn’t syömättä already mean “without eating”?

Syömättä only says without eating, but it does not specify what is (not) eaten.

Adding mitään (anything) gives the more specific idea without eating anything. This is the natural way in Finnish to express the English idea without eating anything at all.

Compare:

syömättä – without eating (in general; object not mentioned)
syömättä mitään – without eating anything (explicitly no food at all)

You almost always add mitään when you want to mirror English anything in a negative context like this.

Why is mitään in the partitive case?

Mitään is the partitive singular of the pronoun mikään (some-/any-thing).

There are two main reasons for the partitive here:

Objects under negation in Finnish are typically in the partitive:
- En syö omenaa. – I am not eating an apple.
Mikään / mikä / mitä and their forms behave like indefinite pronouns (something / anything / nothing), and in negative contexts the form mitään is standard for anything.

So syömättä mitään literally means without eating anything (at all), and the partitive mitään fits both the negative context and the idea of an indefinite, not-specific object.

Is mitään here a kind of “double negative”, like saying without eating nothing?

No. Finnish handles this differently from English.

In English, double negatives like I don’t want nothing are usually considered incorrect or non‑standard. In Finnish, however, negation + mitään is completely normal and not considered a logical double negative.

En syö mitään. – I do not eat anything.
En halua lähteä uimaan syömättä mitään. – I do not want to go swimming without eating anything.

So you should translate mitään as anything, not nothing, when it appears together with a negative verb or a negative construction.

Could I say En halua mennä uimaan syömättä mitään instead of En halua lähteä uimaan syömättä mitään? Is there a difference?

You can say En halua mennä uimaan syömättä mitään, and it is grammatical and understandable.

The nuance:

lähteä uimaan – emphasizes setting off / leaving to go swimming.
mennä uimaan – more neutral go to swim; less focus on the act of departure itself.

In many everyday contexts, mennä uimaan and lähteä uimaan are very close in meaning, and both are used. Lähteä is perhaps a bit more common when you are talking about leaving from home or from your current place to go do an activity.

Is the word order fixed, or can I move syömättä mitään earlier in the sentence?

Finnish word order is fairly flexible, so you can move syömättä mitään around, but the most neutral, natural place is after the main verb phrase, as in the original:

En halua lähteä uimaan syömättä mitään.

Other possibilities:

En halua syömättä mitään lähteä uimaan.
This puts extra emphasis on syömättä mitään (the without eating anything part).
Syömättä mitään en halua lähteä uimaan.
Very strong emphasis: If I have not eaten anything, then I do not want to go.

All of these are grammatical, but the original sentence is the most usual and least marked in everyday speech.

Can syömättä mitään also be used in a positive sentence, or only with negation?

Yes, syömättä mitään can appear in positive sentences as well. The form syömättä itself is not a negative verb; it simply expresses lack of an action (without eating).

For example:

Haluan lähteä uimaan syömättä mitään.
I want to go swimming without eating anything.

Grammatically this is fine; it just means that you actually want the situation where you go swimming and do not eat anything beforehand.

So:

The main clause can be positive or negative (Haluan / En halua).
Syömättä mitään always adds the idea without eating anything, regardless of that.