@geo12345 - For a small lake a short walk away, a sit on kayak and maybe some portage wheels is probably best.  What I would choose in your place anyway.  The main issue would be having a place to store it, preferably out of the elements, when not in use.

I haven't used this one but just as an example this weighs only 40lb and costs less than $400 new.  There are many other similar boats.  Depending where you are, finding something like this used may not be that hard...

https://www.rei.com/product/198179/tahe-ouassou-sit-on-top-kayak

Unless you regularly do a lot of sittups, I'd get something with a good seat back.

Just for interest...I'm not necessarily endorsing its author or their advice although it seems sensible from a brief look...here's a article I found that lists some other boats of this type.  

https://www.kayakhelp.com/ten-best-sit-on-top-kayaks-for-beginners/

Inflatable kayaks are great and if you plan to boat elsewhere could be a good choice since they can be packed inside a vehicle, but good ones are heavy, considering, and expensive and really require a car to get them near the water to inflate.  You have to treat them with some care particularly out of the water, since punctures are possible.  They are not that easy to carry un-inflated and then you have to inflate them.  That requires a fair amount of work unless you use some kind of electric pump which again, generally requires a car.

Pack rafts are light enough to carry and good for what they are meant for (crossing rivers and lakes when backpacking) but although I don't doubt fun can be had in remote places, they don't make great boats for actual boating when compared to a kayak or a canoe.  Again you have to inflate them and punctures can be an issue.