Sentinel-3 OLCI Level 2 Product

Hello everyone! I have downloaded Sentinel-3 OLCI Level 2 Product, but I don’t know how to open it with RGB format in SNAP 7.0.

Did you check up this thread, create RGB S3

Source of the thread

Probably you are using a Land product, right?
They don’t contain spectral information for creating an RGB.
You can colourize the bands like OTCI by the Colour Manipulation.
Is you want to have a natural RGB, you need the corresponding Level 1 product, too.

In general you can create an RGB view in SNAP like this:
If you have opened the product in SNAP then you can simply right-click on the product and choose from the context menu Open RGB image. There you can define how the RGB should be opened.

Thank you very much! I want to know whether Level-1 product needs atmospheric correction? And can you tell me how to implement atmospheric correction of Sentinel-3 Level-1 product? Thank you!

If the level 1 products need an atmospheric correction depends on your application. Not in all scenarios an AC is necessary.
The level 2 products provided by ESA are Atmpherically corrected. The water products also contain spectral information.
In order to apply a AC you can use iCOR.

Many thanks for your replying!