The Hydroelectric Eel is the first fast military unit of the Oceanic Future. It is unlocked with the technology Controlled Lightning. It can also be received by completing the Strange Machines, Keep Calm, Silence, Persuasion (Oceanic), and Black Spots Story Quests.
Compared to the Recon Raider, its predecessor, the Hydroelectric Eel gains 50 defense and 2 range, though attack is kept the same and it has ever so slightly decreased movement. It also has very high bonuses against ranged and artillery units as well as various terrain bonuses, but the best upgrades are the abilities Hides in Bushes (Stealth) and Heat at 20%. It has somewhat modest stats compared to other Oceanic Future Units.
Usage[]
The Hydroelectric Eel is more useful than it appears to be, due to the fact that the Oceanic Future battlefield has a lot more bushes than expected, making its Stealth ability very useful (in fact it is activated the most apart from Hides on Plains (Stealth) of all Stealth units). In addition it has very high movement and good range, meaning it can easily move first and deal significant damage to enemy units before they have reacted (also making them useful for annoying defenses). They are best deployed as armies of 8 against ranged and artillery units, but they can also deal with a small number of light and heavy units as well, as long as they are eliminated quickly.
However, the Hydroelectric Eels will struggle after the Oceanic Future due to the lack of bushes in later battlefields, and their stats will become very weak eventually. Also, the Hydroelectric Eel is not a Flying unit, so they can still be targeted by artillery units.
Against Same Age Units[]
Hydroelectric Eel[]
The best way to take out enemy Hydroelectric Eels is to have them in greater number; this will allow you to get the most first turns and eliminate them before they can do much damage back. It also should be noted that to effectively counter the Hydroelectric Eel, you should take advantage of hiding in bushes.
Gliders[]
As both fast units move together, the Hydroelectric Eel generally has the advantage of hiding in bushes, despite the Gliders' fast mobility. Other than that they are on even terms with each other.
Manta[]
Whilst the Manta is a counter to the Hydroelectric Eel, the Eels' longer range means that they can avoid the Manta's retaliation. However, the Manta may be somewhat hard to kill, due to their bonuses against fast units, and the Manta can still deal considerable damage to the Eel if they are not hidden or if the Eel is within retaliation range.
Scimitar[]
The Scimitar is a threat to the Hydroelectric Eel, especially as they have also very good movement and the Dragon Breath ability, which allows them to deal potentially a lot of damage to the Hydroelectric Eel. The only advantage the Eel has over the Scimitar is their fast first attack.
Sub Cruiser[]
The Hydroelectric Eel is very strong against the Sub Cruiser, but they still have to contend with the Sub Cruiser's annoying retaliation. Despite this, the Eels can hide in bushes, which can give them a very good advantage when fighting the Sub Cruiser, and easily kill Sub Cruisers in two hits.
Nautilus[]
The Hydroelectric Eel is very strong against the Nautilus, with the only drawback being the Nautilus's Force Field ability. Despite this, the Eels can hide in bushes, which can give them a very good advantage when fighting the Nautilus, and the Nautilus can still be easily killed in two hits given a good boost and bonuses in attack.
C.R.A.B. Mech[]
The Hydroelectric Eel is very weak against the Crab Mech, as they have a very high attack, bonuses against fast units and the blast ability, which can easily kill the Eel even if they are hidden. Furthermore, the Reactive Armor ability of the Crab Mech can also greatly reduce the Eel's effectiveness against killing Crab Mechs on the first turn.
Octopod[]
The Hydroelectric Eel is ineffective against the Octopod, especially as the Octopod has great bonuses against fast units as well as very strong attack and defense, making them difficult to kill. However, the Eels can still hide, which can help them deal with a couple Octopods, but they cannot deal much damage against them, and exposed Eels can easily be killed by Octopods.
Turturret[]
The Hydroelectric Eel is very strong against the Turturret, as 8 of them can easily finish 4 Turturrets before they have even had a chance to be alive. In addition, the Turturret is very ineffective at killing the Eels, as they can hide in bushes, but care must still be taken as exposed Eels and nearby Eels can still be damaged quite significantly by the Turturret's Mortar ability.
Medusa[]
The Hydroelectric Eel is only somewhat strong against the Medusa, as the Medusas can move before the Hydroelectric Eel and can still cause some considerable damage to your Eels before they have had a chance to fire, with the added problem that the Medusa has a very high attack. Flying units are much better at sorting out Medusa armies.
Other Military Units[]
Legend: 
= Light Unit Class 
= Ranged Unit Class 
= Artillery Unit Class 
= Heavy Unit Class 
= Fast Unit Class