All Argonians can breathe under water and have a swim speed equal to their walk speed

your Dex score is increased by +2 and your Con score is increased by +1

All Argonians have advantage on saving throws against disease

Argonians have proficiency in stealth

As a bonus action on your turn you can spend a number of hit dice equal to half your level plus your proficiency bonus, and regain that much missing health. You must take a long rest to use this feature again.