Trip to Switzerland --: The arrival--

The use of -- in the title I have never seen before in English. Normally you would use a colon as I have put

I went on a trip to Switzerland from last Saturday through to this Tuesday.

The sentence structure you used will always be 'from ... through to ... ', just forgot the 'to'

It was my very first time to visiting Switzerland, and I was very excited.

You could use the infinitive to visit if you structured the sentence as 'I went to visit Switzerland last Saturday' for example but when you are recounting as you are with 'It was my very first time ...', you need 'visiting' in English. You could also write 'It was the first time I visited Switzerland' as well.

We stayed 3 nights at a hotel in a town called Interlaken, situated between two giant lakes.

The town is surrounded by large mountains and the two lakes, we could get amazing amazing views of 360 degree views.

- In English we put 360 degrees before views in the expression 360 degree views
- Saying 'the lakes' sounds a little weird, I added 'two' to make it clear that you are specifically referring to the two lakes you mentioned in the previous sentence

Apparently, the place is a common tourist destination among people from east Asia such as China, Korea, and Japan -- We saw many shops and restaurants with, Chinese, Korean, and Japanese restaurants, as well as many east Asian travelers speaking those languages.

- Added 'tourist' just to be a bit more explicit that people are holidaying there not working or something
- When describing a restaurant in English, the word restaurant will always be at the end. For an example 'it was a Chinese, super tasty but over the top and noisy restaurant', all these describing going before the word resturant

The atmosphere of the town was very cosy, whileextremely clean but also a tad crowded, and the town was extremely clean.

- The expression is 'a tad ...' i.e a tad busy, a tad expensive, a tad over the top etc. Good job using 'a tad' though, it's something natives would not expect you to use!
- Typically in English for flow, you group positives together and negatives together and then one or the other goes first with the other going afterwards. If you put the positive group first and the negative second it gives a slightly negative connotation then if you start with negative but end with positive. I changed your sentence a bit to but the two positive things first and then the negative thing second. You will also join the positive to the negative with a word like 'but', 'however', 'expect' etc. For example if you wrote it as 'The town was a tad crowded but it was very cost and extremely clean', you start off acknowledging it was a tad crowded (negative) but by writing 'but it was very cosy and extremely clean' you are saying that even though it was a tad crowded you don't mind because it was so cosy and clean ! If you do it the other way around 'The atmosphere of the town was very cosy, extremely clean but also a tad crowded.' then you acknowledge that it was cost and clean that's good but it was a bit crowded which diminished how much you enjoyed it
- FYI cosy is British/Australian English. For American English write 'cozy'

I wondered how this town could be kept this clean while so many tourists visit this place every day.

- Because you are astonished essentially that this place can be kept clean despite the number of tourists visiting writing just 'many tourists' sounds weird because the first half of the sentence expresses astonishment whilst the second just says tourists come basically. Adding 'so' in front of many works though because then you're justifying your astonishment because there are 'SO many tourists'
- A more natural way to write this would be 'I wondered how this town could be kept this clean with so many tourists visiting every day.'

It might be because all the tourists there do love nature and perhaps they simply do not want to ruin the beautiful view of the town and its surrounding nature by littering.

- do is unnecessary here and sounds a unnatural. If you are adding do in a context like this it would be to emphasize that they do love ... contrary to what someone thinks or has said. For example, 'Cats don't love me' said Jane. Marie replied 'That's not true ! They do love you!'. Notice that Marie could have also replied 'That's not true ! They love you!' but adding the 'do' emphasizes that no Jane, you're wrong thinking that they do not love you, they definitely do!

When I arrived there, it was cloudy and rained sometimes.

But, even taking the weather into account, the impression of the town was already much higher thanexceeding my expectations.

- Writing impression doesn't really make sense in this context because 'impression' is used to refer to something that you only had a quick glance at. For example, if you drove past the town but didn't actually stay there you could write 'I had the impression it was a good place' or 'I had the impression it would have surpassed any expectations I would have had' but given you stayed there, it doesn't quite fit
- Rewrote the phrase. Saying '... exceeded my expectations' is a very common way to phrase what you are trying to say

I already really appreciated past me having decided to come here, although it was just a few minutes after the arrival and I haven't started any activities yet.

- I like you using the phrase 'past me', something natives say and is quite cute. It's not formal but for this sort of text it's perfect !
- I'm a little but confused with what you have written though because at the start of the text you write you went to Switzerland and stayed there three nights in a town called Interlaken, proceeded to describe the place and then to say here at the end 'it was just a few minutes after the arrival', not quite what you have written here fits. Apart from that the sentence is grammatically correct though

The town is surrounded by large mountains and the lakes, we could get amazing amazing views ofbsolutely amazing 360 degree views.

Apparently, the place is a common destination among people from east Asia such as China, Korea, and Japan --. We saw many shops and restaurants with Chinese, Korean, and Japanese travelers, as well as many east Asian travelers speaking those languages.

The atmosphere of the town was very cosy, whilezy. Though it was also a tad crowded, and the town was extremely clean.

I wondered how this town could be kept this clean while so many tourists visit this place every day.

It might be because all of the tourists there do love nature and perhaps they simply do not want to ruin the beautiful view of the town and its surrounding nature by littering.

You could also break this into two sentences if you want.

But, eEven taking the weather into account, thehowever, my impression of the town was already much higher than my expectations had been.

I already really appreciated “past me” having decided to come here, although it was just a few minutes after the. I just arrivaled and I haven't started any’m excited to get started on my planned activities! yet.

Not sure if this was exactly what you were going for, but it’s an option.