exit 15 off 93 to exit 1 off 393... go left and follow it all the way around the campus. at the stop sign where the ball fields are you take a right and continue following till you get to the Christa McAuliffe space museum , at the rocket go left and follow till the road ends. On the left behind the hills there is a path you can follow that has good access to fish the NHTI pond. There are many places to fish around the pond so follow it in both directions.
I have not fished Horseshoe pond and am not sure i know where it is.
also there is some access to the Merrimack river behind the ball fields and off the side of the road. The rocks around the bridge allow you to get a lot of shore area but i have only been there once. I actually walked right under the 93 bridge off of the exit 1 / 393 but did not have much time.
exit 17 off 93 follow around the curve and go right. you will go over the river . look to both sides but to the left you will see the old railroad bridges. there is access at the commuter parking lot to get to some water but if you follow down to the rotary and go left , follow past the water works place and take a left if you keep following that road it will end in what looks like an abandoned parking lot, go left after going thru the lot and there is shore fishing and easy boat ramp access. you can also get to the railroad tracks from there and they follow the river. follow the tracks and fish both of these old metal bridges and both of the waters that flow into and out of the river. I have had good luck with smallies and with NUCLEAR SIZED PICKEREL in the inlet areas. I know a lot of people dont like the pickerel but those 25 inch plus ones i dont mind at all. weedless frogs and weedless floating blacklizards. very very slow in the weeds has worked well for me. I have also had decent luck with a big Zara spook in these areas this year.
i love the big topwater hit but listen and read what these other guys say. they have been a wealth of knowledge for me. also search thru this northeast area for other posts that are older. there is so much info hidden in these 400ish pages of old posts. also keep an eye on craigslist, everyone in a while there will be a free beat up canoe or small boat someone just wants to get rid of for free. All you need is a life jacket , an oar to go with it some rope all free on craigslist with time and a rock off the side of the road for an anchor. but dont forget though, there are lots of fish you can catch from shore. My personal best although less than 5 lbs comes from shore. Have fun. If i get up in your area with no kids and a seat available in my 12 foot jon boat, i will try to get in touch with you.