At the bottom of section 2.4 in the Hbase Documentation, there is a section about Browsing the web UI that makes several references to port 16610.
"In HBase newer than 0.98.x, the HTTP ports used by the HBase Web UI changed from 60010 for the Master and 60030 for each RegionServer to 16610 for the Master and 16030 for the RegionServer.
If everything is set up correctly, you should be able to connect to the UI for the Master http://node-a.example.com:16610/ or the secondary master at http://node-b.example.com:16610/ for the secondary master, using a web browser. If you can connect via localhost but not from another host, check your firewall rules. You can see the web UI for each of the RegionServers at port 16630 of their IP addresses, or by clicking their links in the web UI for the Master."
This is the wrong port; it should instead be 16010. The correct port is listed in Section 6: http://hbase.apache.org/book.html#confirm
This might seem like a pretty minor issue, but it took me a couple hours to figure out.