Summary: Humans colonize the universe. One of those space ships crashes on a water planet of Tau Ceti. The crew can’t survive but they create genetically changed seeds in the form of water adapted, really tiny humans who have to fight their way against a hostile environment under water. After a few generations, they get curious and have to break the barrier between water and the air above: the eponymous surface tension.
Review: Blish called the changed humans „pantropy“, but nowadays we’d say post-human. I wasn’t able to envision a couple of the technical descriptions when they built the air ship – maybe, I have missed a couple of logical consequences because of that.
I didn’t buy into the first part’s shipwreck colonialization setting where they weren’t able to survive but were able to instantly generate a working genetic transformation.
Also, the microscopic downsizing just wouldn’t work – I would like to mention that you need more computing power in the brain than just that handful of neurons if you want to communicate and innovate. Also, some physics laws like thermodynamics with volume and surface relationship in microscopic dimension work against the story’s logic. This shouldn’t have slipped the author’s attention.
Setting this flaws aside, I really liked the narration and the characters. The exotic location and different angle that the humans have to work against makes this story outstanding of the otherwise typical trope of „back to primitives, rediscover technology“ awe. It certainly feels like a golden age SF without being too pulpish. The plot is clever and thought provoking.