SentinelHub EO Browser is, as the name suggests, a browser based explorer of Sentinel imagery

You can even download subsets of the data for free (requires login though). It's one of the simplest ways to get started exploring Sentinel imagery IMHO

https://apps.sentinel-hub.com/eo-browser/

The Planetary Computer from Microsoft has an explore tool, which includes Sentinel-1 at any time and location, rendered on-the-fly. Free open access. No account required.

https://planetarycomputer.microsoft.com/explore?c=11.6778%2C...

Seems like https://dataspace.copernicus.eu/browser/ is the place to go.

Looks like you need to register for a (free) account, though.