In this talk I will discuss some of the problems arising in connection with the dynamics of polymers under confinement (such as proteins traversing transmembrane pores). Confinement often partitions a polymer's configuration space into distinct basins of attraction separated by large free energy barriers. Because of the predominantly entropic nature of such barriers, transitions between different basins often cannot be characterized in terms of dominant pathways. I will particularly focus on the problem of a polymer reversal inside a long pore and compare exact rate calculations with predictions from polymer scaling theory and with various approximate theories.