Neanderthal Genome Study...

[Anomalocaris]

There have been multiple ice advances and retreats and, iirc, the last one did not reach so far into the Ukraine but every time the ice melted it had to drain somewhere.

And Robert Bednarik has demonstrated that HE would have needed at least rafts with oarsmen to colonize the outer island of Indonesia on the far side of the Wallace Line. The vegetation mat hypothesis was just a wing and a prayer by HSS defenders who thought that cavemen were ignorant brutes.

No, boats are not that exotic a technology. All you need is someone to notice that a log floats and you are halfway there. That said, the idea that we will ever find an intact boat from 500k ypb is a pipe dream. Boats tend to be used near water and water breaks down organic material eventually. And nature has all the time it needs.

I'm afraid we have to handle this one by deduction. If HE got to the Indonesian islands he either walked, flew or sailed. I think we can rule out "flew." And if the water was never less than 6 feet deep no one walked there.