Answer: No especially when dealing with Slaanesh. Lust is simply a strong sexual desire, whereas love is a strong feeling of deep affection. EDIT: Not that the latter really exists in the wake of the 41st millenium.
Not really the use of 'love' that I was going for... It's well documented that Slaanesh' gifts include, um, let's say sexual options not previously available to the chosen.
Space Marines have a third lung called the multi-lung, and it doubles as gills. So they can either swim or just walk underwater whenever they need
But you would also have to question their durability with the pressures of the depth of water they are in, that is if you were to plop one in an ocean without armor of any kind.
It is difficult for them as they are Heavier than a normal human their size should be, they also have little purpose in doing so as their armor is a sealed environment which can probably withstand depths of a couple hundred feet (educated guess from my scuba exp) but can swim, they do in the Blood Angels second omnibus (3rd book) because they are already underwater in subs and don't want to sink to the seafloor, and in the Space Wolf Second Omnibus first or second book, because they are in a pipe system and are unsure where it would take them. Also the multi-lung doesn't act as a set of gills, it allows them to hold their breath much longer if i remember the codex right its supposed to be an average of 20 minutes, but they can't breathe the water
"Phase 9: This additional lung activates when a Space Marine needs to breathe in low-oxygen or poisoned atmospheres, and even water." --Creation of a Space Marine, as hosted on GamesWorkshop's old website
A lot of dark-skinned real-life humans find swimming harder because they have a much denser bone structure. You don't see a lot of African swimming champions - their long-limbed bodies are much better suited for running. In W40k the SM are even heavier but they would likely also have the genhanced size and muscles to support their frame. I would imagine the knowledge of swimming is as easy to acquire for most of them as it is for any human. It's also fairly safe to assume that most homeworlds that support normal human life have some kind of water on them. Since space marines are supposed to be able to survive almost anywhere, I would imagine that swimming would almost certainly be a part of their basic training. We came across this question in our Deathwatch RPG group and after a lot of LOLs we decided that they could swim normally as a basic skill but obviously power armour would probably weigh them down unless it had some kind of flotation device installed.
