Manuscript handles a very important topic of creating a database for hydrological studies. Authors combined various satellite datasets with an aim to provide consistent output of surface water extent of lakes and rivers, water level of inland water bodies, water storage anomaly of hydrological basins, lakes and reservoirs, and river discharge for large and small rivers. Paper is original and unique. It also consists of huge science behind the output datasets. Despite its advantages, some shortcomings may be found. These are listed below:

1. Paper is very long. It is sometimes hard for the reader to stay focused on the main research idea. I would advise the authors try to shorten the manuscript by putting some less important information into Appendices. It would make the paper more clear.
2. There are too many technical details provided within the manuscript. These could be moved, as mentioned above.
3. I am not really sure why SWOT mission is mentioned several times across the manuscript. It does not bring any new conclusion or outlook on the results the authors provide. I would advise these comments to be removed.
4. I really miss any comparison of dataset to the existing databases. I mean from the Figures you provide it is clear that your dataset is more or less similar to the existing ones, but maybe some statistics would be useful. At least to show why your dataset is unique and why it should be used instead of others.
5. Main advantages of database should be pointed in the introduction section. It is now not really clear where the uniqueness of your database is. While I believe it is new, it should be strictly pointed at the beginning of the manuscript.
6. I would advise the authors to clearly divide the manuscript into sections covering introduction, datasets, methodology, results and comparisons, conclusions. For now all the above sections are somehow mixed, which made it hard for me to follow the main topic.
7. It is not really clear which satellite missions are employed for creating individual outputs. (Or maybe I missed it somewhere?). It would be better if all datasets are strictly listed or mentioned/described.

The paper presents a rather unique dataset that provides several hydrological variables obtained with satellite data related to: 1) water level time series of rivers and lakes; 2) surface water extent of rivers and lakes; 3) terrestrial water storage anomaly; 4) water storage anomaly for lakes and reservoirs; 5) river discharge estimates for rivers. Globally, I found the idea to collect all these variables together quite interesting and useful for hydrological applications even if the dataset is far from to be exhaustive and complete, at least for some variables: for example, water level and water storage anomaly cover quite all the globe, whereas the surface water extent and the river discharge are estimated only for some stations (and sometimes not coincident).

About the paper, it is very long with a lot of information and a few innovative elements. Actually, most (maybe all) of the procedures to derive the hydrological products have been already published. Therefore, the paper shows a collection of already published algorithms and procedures with a remark of the main results and validation. I really appreciated the comparison with other datasets, but I am quite dubious about the general content.

In addition, the citation to four unpublished papers (Behnia et al. and Elmi et al.) makes this paper more uncertain for two reasons: first, the content described in the papers is not still accepted by the scientific community, and if from one hand it is good for the originality of the content of  this article, on the other hand, no many details are provided on that specific procedures to allow the acceptance; second, no way to check the under review or submitted papers, to verify the originality of the content of this paper.

So, despite it is a big paper with a lot of science behind, I think it is not good enough to demonstrate the novelty of the datasets.