OL_EFR L1C of sentinel 3

I’m kinda confused since there are level 1 and level 2 data of sentinel 3. I downloaded the free s3 l1c ol_efr from copernicus hub.
Does it mean that the data that i downloaded is only georefenced and has no radiometric calibration ?
So, i still need to do some preprocessing since I want to get the chl-a abd tsm by applying c2rcc?

I am new to snap and I’ve been searching for documentations and references. If you guys have something that can help me, please tell me. Thank you!

That’s true. For chl-a or other higher level variables you need to process the L1C data, For example with the C2RCC or the Mph/Chl processor.
But you can also download the L2 Water products from the Coda by Eumetsat (https://coda.eumetsat.int/#/home). In these products, you can find chl data, already.

ESA and Eumetsat have split the responsibility for land and water processing, hence we have this user-unfriendly split of data products.

More info about the different product level can be found here: https://sentinel.esa.int/web/sentinel/user-guides/sentinel-3-olci/processing-levels/level-1.