Public Data Sets on AWS provides a centralized repository of public data sets that can be seamlessly integrated into AWS cloud-based applications. AWS is hosting the public data sets at no charge for the community, and like all AWS services, users pay only for the compute and storage they use for their own applications. Learn more about Public Data Sets on AWS and visit the Public Data Sets Forum.
The IRMA Portal "provides easy access to National Park Service applications that manage and delivery resource information to parks, partners and the public." (source: website) Access to park visitor use statistics, water quality and quantity data, occurrence and status of species in more than 300 NPS national parks, and documents and datasets about natural and cultural resources in the parks.
From the National Aeronautics and Space Administration (NASA)
"This site is a continually growing catalog of publicly available NASA Datasets, APIs, Visualizations, and more."