The device spotted as Samsung Poseidon has not appeared on GFXBench and it looks like AT&T should add it to its portfolio soon, although it has not been confirmed officially yet. The GFXBench listing reveals most hardware specs of the Galaxy S7 Active, which make it similar to the Galaxy S7 Edge.
Samsung Galaxy S7 Active has the model name SM-G891A and is powered by a Qualcomm Snapdragon 820 SoC, next to 4 GB RAM and 32 GB internal storage. The 5.5-inch handset has two cameras that offer 5 MP and 12 MP. Being an "Active" handset, it will probably come rubber front buttons and a plastic/polycarbonate body. An Active key should also be included to make this handset stand out from the crowd.
In addition to the above, a fingerprint reader will probably be included as well. We will get back to the SM-G891A once it gets released via AT&T as it usually happens with Samsung Galaxy Active smartphones, so stay tuned.