For Haslab water vehicles, the Moray for Cobra and WHALE for Joes. Both would be rather large vehicles. But I think they could still make the WHALE and just trim out some of the features, like the sled.
Or maybe instead of the WHALE, what about the Tactical Battle Platform for the Joes? It would pair well with the Moray, as they were in a classic issue of the Marvel comic (their comic debut?).
Smaller, retail water vehicles would be great too. Moccasin for ~$100 for Cobra. And a Devilfish for Joes ~$75.
Random thought regarding a Haslab Snow Cat.
What if one of the tiers is Tundra Stalker? And his kayak can store on the back of the Snow Cat. While I do think this look for Stalker is popular enough to succeed at retail, he'd have to be at some kind of deluxe pricepoint. Making him a bonus for the Haslab may make sense. His kayak could also be reused down the road with an Adventure Team set, should they decide to make Adventure Team stuff. I'd rather have Haslab bonus figures be variations of existing characters, and new-to-the-line characters be available at retail.