Learn Hardcore Finnish: Harrastan maantiedettä ja luen karttoja netissä iltaisin. - I am into geography and read maps online in the evenings.

Harrastan is the 1st person singular form of harrastaa, which means “to do something as a hobby / to be into something / to pursue (something) in one’s free time.”

So Harrastan maantiedettä is closer to:

“I’m into geography.”
“Geography is my hobby.”
“I study geography as a hobby.”

It’s stronger and more regular than just “I like geography”; it suggests you actively spend time on it.

Why is it maantiedettä and not maantiede? What case is that?

Maantiedettä is the partitive singular of maantiede (“geography”).

The verb harrastaa almost always takes its object in the partitive case. So:

harrastaa + partitive
- Harrastan maantiedettä. – I’m into geography.
- Harrastan jalkapalloa. – I play football as a hobby.
- Harrastan valokuvausta. – I do photography as a hobby.

The form is:

maantiede (nominative) → maantiedettä (partitive, one kind of “-e” word pattern).

Using maantiede in nominative here (Harrastan maantiede) would be incorrect.

What nuance difference is there between Harrastan maantiedettä and saying “I like geography” in Finnish?

To express “I like geography,” you might say:

Pidän maantiedosta.
Tykkään maantiedosta. (more colloquial)

Differences in nuance:

Harrastan maantiedettä
- You actively do geography-related things regularly, as a hobby (reading, studying, exploring maps, etc.).
Pidän / Tykkään maantiedosta
- You like geography; it doesn’t necessarily say you follow it as an active hobby.

So the given sentence emphasizes regular, hobby-like engagement.

What is the form luen from? Why not lukean or something like that?

The basic verb is lukea (“to read”).

Conjugation in 1st person singular present:

lukea → luen (“I read”)

This change happens because of consonant gradation:

The stem alternates between luk- (strong) and lu- (weak).
In the present tense 1st person, the weak grade is used: luen, not lukean.

Other examples:

Hän lukee – he/she reads
Me luemme – we read

Why is it karttoja and not kartat for “maps”?

Karttoja is the partitive plural of kartta (“map”).

Forms of kartta:

Nominative plural: kartat – “the maps” (as a whole set, definite group)
Partitive plural: karttoja – “(some) maps,” “maps (in general / some amount)”

In this sentence, luen karttoja suggests:

You read maps in general / some maps, not a specific complete set.
Finnish often uses the partitive when talking about an indefinite quantity or ongoing activity.

If you said luen kartat, it would sound like you’re reading through a definite, known list of maps, as if you have a pile you must finish. That’s possible but a very different nuance.

Is there a rule for why kartta becomes karttoja in the partitive plural?

Yes, it follows a common pattern for -a/-ä words with double consonants.

Base word: kartta
Stem with strong grade: kartta- (double t)
Partitive plural ending: -ja / -jä

Between the stem and -ja, the double consonant often remains, but vowels may adjust:

kartta + ja → karttoja

You see similar patterns in other words:

kissa → kissoja (cats, partitive plural)
pallo → palloja (balls, partitive plural)

So karttoja is the regular, correct partitive plural form.

What does netissä literally mean, and what case is that?

Netissä is the inessive case of netti (“the net,” colloquially “the internet”).

netti – (the) net
netissä – “in the net,” used idiomatically as “on the internet”

The inessive case -ssa / -ssä generally means “in / inside / at”:

kaupassa – in the shop
koulussa – at school
netissä – on the internet

So luen karttoja netissä literally: “I read maps in the net,” understood as “on the internet.”

How is netissä different from netistä or nettiin?

These are different local cases with different meanings:

netissä – inessive: “in/on the internet” (location)
netistä – elative: “from the internet” (origin)
nettiin – illative: “to the internet” (direction towards)

Examples:

Luen karttoja netissä. – I read maps on the internet.
Löysin tietoa netistä. – I found information from the internet.
Lataan kuvia nettiin. – I upload pictures to the internet.

What does iltaisin mean exactly, and how is it formed?

Iltaisin means “in the evenings,” “on evenings,” implying a habitual or regular action.

Formation:

Base noun: ilta – evening
Adverbial/habitual form: iltaisin – “(habitually) in the evenings”

The ending -isin is used to form adverbs of repeated time:

aamu → aamuisin – in the mornings
ilta → iltaisin – in the evenings
viikonloppu → viikonloppuisin – on weekends

So iltaisin tells us this happens regularly, not just once.

What is the difference between iltaisin and illalla? Both seem to mean “in the evening.”

Both relate to the evening, but they differ in aspect and habituality:

illalla
- Means “in the evening / this evening / on that evening” (more concrete, one particular time).
- Luen karttoja netissä illalla. – I’ll read maps on the internet this evening / in the evening (today / that day).
iltaisin
- Means “in the evenings (generally), in the evenings as a habit”.
- Luen karttoja netissä iltaisin. – I read maps on the internet in the evenings (as a regular habit).

In the given sentence, iltaisin tells us it’s a repeated, usual routine.

Why is there no word for “I” in the Finnish sentence? Where is the subject?

In Finnish, the personal ending on the verb usually makes the subject clear, so the pronoun is often omitted.

harrastan – “I (harrastaa)” – the -n ending marks 1st person singular
luen – “I (lukea)” – again, -n marks “I”

You could say:

Minä harrastan maantiedettä ja luen karttoja netissä iltaisin.

But minä is not necessary unless you want to emphasize the subject (e.g. “I, as opposed to someone else, do this”).

Can I change the word order, for example: Iltaisin harrastan maantiedettä ja luen karttoja netissä?

Yes, that word order is natural and correct. Finnish word order is relatively flexible, and you can move elements to emphasize them.

Original: Harrastan maantiedettä ja luen karttoja netissä iltaisin.
Alternative: Iltaisin harrastan maantiedettä ja luen karttoja netissä.

In the second version, Iltaisin is brought to the front, so you emphasize the time (“In the evenings, I …”). The basic meaning remains the same.

If I want to say “I study geography and read maps on the internet in the evenings” (more like serious study, not just a hobby), how would I change the sentence?

You’d usually switch harrastaa to opiskella (“to study” in an educational sense):

Opiskelen maantiedettä ja luen karttoja netissä iltaisin.

Nuances:

Opiskelen maantiedettä – I study geography (as a school/university subject or serious self-study).
Harrastan maantiedettä – I’m into geography as a hobby, possibly self-directed and not formal.

Both are grammatical; the choice depends on whether you want the hobby-feel or the formal-study feel.