Learn Farsi: از آنجا که مسیر تنگ است، غارنوردی در اینجا خیلی سخت است. - Since the route is narrow, spelunking here is very hard.

Literally, az ânjâ ke means 'from there that,' but it is a common conjunction meaning 'since' or 'seeing that' to introduce a reason. Because it states a known fact rather than a wish or doubt, it takes a regular indicative verb. Here, it simply uses the standard present tense ast (is).

How is the word ghâr-navardi (spelunking) formed?

It is a compound noun. ghâr means 'cave'. navard is a root meaning to travel or traverse, and the -i suffix turns the whole thing into an activity or sport. You will see this same -navardi pattern in other activities, like kuh-navardi (mountain climbing/hiking).

Can the word tang (narrow) be used in other contexts?

Yes! While it means 'narrow' here for a route (masir), tang is very frequently used to mean 'tight'. For example, you would use it to describe clothes that are too small or tight-fitting. It is also used in the famous idiom del-am tang ast (my heart is tight), which means 'I am homesick' or 'I miss someone'.

Could we just say injâ instead of dar injâ for 'here'?

Yes, in spoken or everyday Farsi, you will almost always just hear injâ (here) on its own. Keeping the preposition dar (in) to make dar injâ (in here) makes the sentence slightly more formal and emphasizes being physically inside the specific location.