Best route from Science Park to Langone Park (Bill Russell underpass?)

I’m unfamiliar with this part of Boston from a cycling perspective. I’ll be riding east on Esplanade bike path, from Hatch Shell to Science Park. I want to go to Langone Park, on North End waterfront. I’ve heard about the new Bill Russell bridge underpass but have heard it’s hard to find. Also, will Esplanade be passable tomorrow morning, given preparations for the fireworks show? TIA