use strict;
use warnings;

my %hash = (
	'key 1' => {
		'innerhash1 key 1' => 'some data',
		'innerhash1 key 2' => 'some more data',
	},
	'key 2' => {
		'innerhash2 key 1' => 'even more data',
		'innerhash2 key 2' => 'a bit more data',
	},
);

foreach my $key (keys %hash) {
	foreach my $inner_key ( keys %{$hash{$key}} ) {
		print "$inner_key $hash{$key}->{$inner_key}\n";
	}
}