First, your snapshots are already stored in S3 but you will not be able to see it. So, why do you want to keep the same contents in S3?
But still, I will provide you with a way to do this. Follow these steps, so that you can get your EBS contents into S3.
- First, create an EBS volume with the available snapshot
- Create an EC2 instance and attach this volume to it
- Now, copy the contents of this volume into S3 straight from your instance using AWS CLI commands
- Terminate the EC2 instance and delete the EBS volume to stop getting billed for them
This is one way to do it, but if you provide a more explanatory question, I can provide a better solution. Hope this helps!