Blue Robotics Forum
The Blue Robotics forum is a community of marine roboticists and ArduSub users. This is a great place to ask questions, and share your projects and ideas.
The ArduPilot Forum is a community of ArduPilot users. There is a lot of information on troubleshooting, hardware and software developments, and technical projects.
The ArduSub gitter is a chatroom to discuss ArduSub code, but we're happy to help anyone who drops by.